98 - Glossary

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Every key term from the Introductions of all guides, A to Z, with a link to the guide that explains it. Generated by tools/build_glossary.py from the "Key terms" tables; do not edit by hand.

Some terms appear in several guides with a meaning specific to that context (for example "Token" in HTTP authentication and in LLMs).

Jump to: A B C D E F G H I J K L M N O P Q R S T U V W Z

A

Term	Meaning	Guide
Action	Reusable building block from the Marketplace (actions/checkout@v4)	44 - GitHub Actions (CI/CD)
Activate	Switch the terminal to use the environment's Python	11 - Python Virtual Environment
Adapter	The small trained LoRA weights	37 - Fine-tuning
Agent	LLM + tools + loop that pursues a goal autonomously	32 - AI Agents
Agentic RAG	The LLM decides when and what to search, using a search tool	31 - RAG (Retrieval-Augmented Generation)
Alias	Short name for a command (ls -> Get-ChildItem)	03 - Terminal and PowerShell
Anchor	Link target created from a heading (#1-headings)	02 - Markdown
ANN	Approximate nearest neighbour: fast, slightly inexact search	30 - Embeddings and Vector Databases
Answers file	.copier-answers.yml in the generated project: template source, version and answers	51 - Project Templates
API	Application programming interface: the agreed way one program asks another to do something	01 - Core Concepts: Code, Packages, APIs and SDKs
API	Interface that lets programs talk to each other	40 - FastAPI
API gateway	The single entry point that routes requests to services (here: the Nginx proxy)	50 - Project Structure: Python Microservices + Frontend
API key	A secret string that proves who you are to an API (and who pays)	01 - Core Concepts: Code, Packages, APIs and SDKs
API key	Secret that identifies and bills you; keep in env vars	27 - LLM APIs
App string module:attribute	Where Uvicorn finds the app, e.g. app.main:app	41 - Uvicorn (ASGI Server)
Arrow	In-memory columnar format shared by Polars, DuckDB, pandas	19 - Polars and DuckDB
Artifact	Files saved from a run (reports, builds)	44 - GitHub Actions (CI/CD)
Artist	Anything drawn: lines, text, patches	21 - Matplotlib
ASGI	Async interface between Python web servers and apps	41 - Uvicorn (ASGI Server)
ASGI app	Object the server calls (your app = FastAPI())	41 - Uvicorn (ASGI Server)
ASGI server (Uvicorn)	The program that runs your app and handles connections	40 - FastAPI
Assertion	A check that must be true	15 - pytest
await	Pause here until the awaited thing finishes; let other tasks run	14 - Async Python
Axes	One plot area inside a figure (with its x and y axis)	21 - Matplotlib
Axes-level function	Draws one plot into a Matplotlib Axes (boxplot)	22 - Seaborn
Axis	A dimension: axis=0 rows direction, axis=1 columns direction	17 - NumPy

B

Term	Meaning	Guide
Backend	Where state is stored (local file, Azure Storage, Terraform Cloud)	47 - Terraform
Backpropagation	Computing gradients from the loss back through the layers (loss.backward())	24 - PyTorch
Base model	Model before your fine-tuning (use an instruct model for chat tasks)	37 - Fine-tuning
Base vs instruct model	Base continues text; instruct / chat follows instructions	25 - Hugging Face
Bash	The default shell on most Linux systems	04 - Linux
Batch API	Async bulk processing at lower cost	27 - LLM APIs
Batch / epoch	Group of samples per step / one full pass over the data	24 - PyTorch
Blocking call	A normal function that waits without letting others run (time.sleep, requests.get)	14 - Async Python
Body / payload	The data sent, usually JSON	09 - HTTP and APIs
Branch	An independent line of development	05 - Git and GitHub
Breakpoint	A line where the debugger pauses	06 - VS Code
Broadcasting	Automatic stretching of arrays with different shapes	17 - NumPy
Broker	The queue storage that holds jobs (Redis, RabbitMQ)	42 - Redis, Caching and Task Queues
Buffering	Proxy collects the response before sending (breaks streaming if on)	45 - Nginx, Reverse Proxy and HTTPS
Build context	The folder Docker sends to the builder; files outside it cannot be copied into the image	50 - Project Structure: Python Microservices + Frontend

C

Term	Meaning	Guide
Cache hit / miss	Found in cache / not found (compute and store)	42 - Redis, Caching and Task Queues
Caching	Keep expensive objects (models, clients, indexes) between reruns	39 - AI User Interfaces (Streamlit, Gradio, Chainlit)
Catastrophic forgetting	Loses general abilities after narrow training	37 - Fine-tuning
Cell	One block of code or Markdown	16 - Jupyter
Chain	Fixed sequence of steps (prompt -> model -> parser)	33 - Agent Frameworks
Chain of thought	Letting the model reason before the final answer	28 - Prompt Engineering
Character class	A set of allowed characters, e.g. [a-z] or \d	07 - Regex
Checkpointer	Saves state so runs can resume / be inspected	33 - Agent Frameworks
Checkpoint / model ID	organisation/model-name, e.g. sentence-transformers/all-MiniLM-L6-v2	25 - Hugging Face
Chunk	A piece of a document stored and retrieved as a unit	31 - RAG (Retrieval-Augmented Generation)
Chunk overlap	Repeated text between neighbouring chunks so ideas are not cut in half	31 - RAG (Retrieval-Augmented Generation)
Citation	Reference to the source of each claim	31 - RAG (Retrieval-Augmented Generation)
CLI	Command-line interface: a program you use by typing commands and flags (git, uv, docker)	01 - Core Concepts: Code, Packages, APIs and SDKs
Client	The object (or program) that sends requests; in SDKs, client = anthropic.Anthropic()	01 - Core Concepts: Code, Packages, APIs and SDKs
Client	Connection inside the host to one server	34 - MCP (Model Context Protocol)
Client / server	Who asks / who answers	09 - HTTP and APIs
Client tools	Run by your code	29 - Tool Use (Function Calling)
Cluster	Control plane + worker nodes	46 - Kubernetes
Cmdlet	A PowerShell command (Get-ChildItem)	03 - Terminal and PowerShell
Code-based grading	Deterministic checks (exact match, regex, JSON valid, tests pass)	35 - Evals and Observability
Code fence	Three backticks that start / end a code block	02 - Markdown
Coercion	Converting compatible values ("1" -> 1)	13 - Pydantic
Collection / index	A named set of vectors in a vector DB	30 - Embeddings and Vector Databases
Colormap (cmap)	Mapping from values to colours	21 - Matplotlib
Command Palette	Ctrl+Shift+P: search box for every command	06 - VS Code
Commit	A saved snapshot with a message	05 - Git and GitHub
Completion / output	Tokens the model generates	26 - LLM Fundamentals
Compose	Tool to run several containers from one YAML file	43 - Docker
Compose override file	A second Compose file whose settings are merged over the first (for example for development)	50 - Project Structure: Python Microservices + Frontend
Computer use	Agent operates a GUI (screenshots, clicks, typing)	32 - AI Agents
Concurrency	Many tasks in progress at once (interleaved)	14 - Async Python
ConfigMap / Secret	Configuration / sensitive values injected into pods	46 - Kubernetes
Conflict	Two branches changed the same lines; you decide the result	05 - Git and GitHub
Container	A packaged, isolated copy of an app with everything it needs to run (Docker)	01 - Core Concepts: Code, Packages, APIs and SDKs
Container	Running instance of an image	43 - Docker
Content block	One piece of the response: text, thinking, tool_use, ...	27 - LLM APIs
Context engineering	Curating all information in the context window	28 - Prompt Engineering
Context length (num_ctx)	Max tokens per request the server allocates for	36 - Local and Self-Hosted LLMs
Context window	Max tokens the model can consider at once (prompt + output)	26 - LLM Fundamentals
Continued pretraining	More next-token training on raw domain text	37 - Fine-tuning
Cookiecutter	Older, widely used Python templating tool; generates once, no built-in update	51 - Project Templates
Copier	Python tool that renders templates from questions and can update generated projects later	51 - Project Templates
copier.yml	Copier's configuration: questions, defaults, validators and settings	51 - Project Templates
Coroutine	What calling an async def function returns; it does nothing until awaited	14 - Async Python
Corpus / knowledge base	All documents you can retrieve from	31 - RAG (Retrieval-Augmented Generation)
Cosine similarity	Similarity of direction between two vectors (-1 to 1; higher = more similar)	30 - Embeddings and Vector Databases
Coverage	Share of code lines executed by tests	15 - pytest
Crew	Group of role-based agents with tasks (CrewAI)	33 - Agent Frameworks

D

Term	Meaning	Guide
Database	A collection of tables managed by a database system	20 - SQL
Data exfiltration	Sneaking private data out (e.g. via a URL or email)	38 - AI Security and Responsible AI
DataFrame	A table: rows and named columns	18 - Pandas
Data leakage	Information from the test data or the answer sneaks into training	23 - Scikit-learn
Data ownership	Rule that only one service reads and writes a given database	50 - Project Structure: Python Microservices + Frontend
Data source	Read-only lookup of something that already exists	47 - Terraform
DDL / DML	Statements that define structure (CREATE) / change data (INSERT)	20 - SQL
Deallocate	Stop the VM and its compute billing (disk still billed)	49 - Azure VM + Linux + Ollama
Delimiters / XML tags	Markers that separate instructions from data (<document>...</document>)	28 - Prompt Engineering
Dependency	A package your project needs in order to run	01 - Core Concepts: Code, Packages, APIs and SDKs
Dependency	A package your project needs (pandas, fastapi)	12 - uv
Dependency group	Extra packages only for some uses, e.g. dev (pytest, ruff)	12 - uv
Dependency injection	FastAPI passes shared things (DB, settings) into endpoints via Depends	40 - FastAPI
Deployment	Keeps N identical pods running; handles rolling updates	46 - Kubernetes
Deserialize / load / parse	Text -> Python object (json.loads)	08 - YAML, JSON, TOML and .env
Device	Where computation runs: cpu, cuda (NVIDIA GPU), mps (Apple GPU)	24 - PyTorch
Dimension	Length of the vector (384, 768, 1024, 1536, 3072 ...)	30 - Embeddings and Vector Databases
Direct injection	The user themselves types the malicious instructions ("jailbreak")	38 - AI Security and Responsible AI
Distance	Opposite of similarity (smaller = closer)	30 - Embeddings and Vector Databases
Distillation	Training a small model on outputs of a big model	37 - Fine-tuning
Distribution (distro)	A packaged Linux version: Ubuntu, Debian, Fedora	04 - Linux
DNS A record	Maps a domain name to your server's IP address	45 - Nginx, Reverse Proxy and HTTPS
Dockerfile	Recipe that builds an image	43 - Docker
DPI	Resolution of saved images	21 - Matplotlib
Drift	Real infrastructure changed outside Terraform	47 - Terraform
dtype	The single data type of all elements (int64, float64)	17 - NumPy
dtype	Data type of a column (int64, float64, object, datetime64)	18 - Pandas

E

Term	Meaning	Guide
Embedding model	Model that converts text to vectors	30 - Embeddings and Vector Databases
Embedding model	Model that turns text into vectors for search / RAG	49 - Azure VM + Linux + Ollama
Embedding / vector	List of floats representing meaning	30 - Embeddings and Vector Databases
Endpoint	One URL + method of a web API, e.g. POST /v1/messages	01 - Core Concepts: Code, Packages, APIs and SDKs
Endpoint	A URL + method that does one thing (POST /v1/messages)	09 - HTTP and APIs
Endpoint / route	A URL + method your API answers (GET /items)	40 - FastAPI
Environment	Deployment target with its own secrets and protection rules	44 - GitHub Actions (CI/CD)
Environment variable	A named setting given to a program by the operating system (ANTHROPIC_API_KEY)	01 - Core Concepts: Code, Packages, APIs and SDKs
Epoch	One pass over the training data	37 - Fine-tuning
Eval set / dataset	Collection of test cases (input + expected / reference + metadata)	35 - Evals and Observability
Event loop	The scheduler that runs coroutines and switches between them	14 - Async Python
Event loop	asyncio scheduler handling many connections in one process (14)	41 - Uvicorn (ASGI Server)
Event / trigger (on)	What starts the workflow	44 - GitHub Actions (CI/CD)
Exception	Python's way of signalling an error; it stops the program unless your code handles it	01 - Core Concepts: Code, Packages, APIs and SDKs
Excessive agency	Model has more tools / permissions / autonomy than needed	38 - AI Security and Responsible AI
Execution count	The number [5] showing the order cells ran	16 - Jupyter
Expression	Polars building block: pl.col("a") * 2	19 - Polars and DuckDB
Extension	Add-on that adds features	06 - VS Code

F

Term	Meaning	Guide
Facet	One small plot per category value (col=, row=)	22 - Seaborn
Features (X)	Input columns the model learns from	23 - Scikit-learn
Few-shot / multishot	Instructions plus a few input -> output examples	28 - Prompt Engineering
Field	One attribute with a type (and optional rules / default)	13 - Pydantic
Figure	The whole image / window	21 - Matplotlib
Figure-level function	Creates a whole figure, can split into facets (catplot)	22 - Seaborn
Fine-tuning / post-training	Further training to follow instructions, be helpful and safe	26 - LLM Fundamentals
Fixture	Reusable setup (data, client, temp folder) injected by name	15 - pytest
Flag	Option that changes matching, e.g. ignore case	07 - Regex
Flaky test	Sometimes passes, sometimes fails (timing, randomness, network)	15 - pytest
Foreign key	Column that links to another table's primary key	20 - SQL
Forward pass	Input through the model to get predictions	24 - PyTorch
Framework	A larger structure that calls your code at the right moments (FastAPI, React, pytest)	01 - Core Concepts: Code, Packages, APIs and SDKs
Full fine-tuning	Update all weights (needs lots of GPU memory)	37 - Fine-tuning

G

Term	Meaning	Guide
Gated model	Needs you to accept a licence and log in (e.g. some Llama models)	25 - Hugging Face
GFM	GitHub Flavored Markdown: standard Markdown plus tables, task lists, alerts	02 - Markdown
GGUF	File format for quantized models used by llama.cpp and Ollama	36 - Local and Self-Hosted LLMs
GitHub template repository	A repository marked as a template so "Use this template" creates a copy with fresh history	51 - Project Templates
Graceful shutdown	Finish in-flight requests before exiting	41 - Uvicorn (ASGI Server)
Grader / scorer	Function that scores an output	35 - Evals and Observability
Gradient	Direction and size to change each weight to reduce loss	24 - PyTorch
Graph	Nodes (steps) + edges (transitions) + shared state (LangGraph)	33 - Agent Frameworks
Grounding	Basing answers on provided sources / tools	26 - LLM Fundamentals
Grounding / faithfulness	Answer supported by the retrieved text	31 - RAG (Retrieval-Augmented Generation)
Group	Part of a pattern in ( ) you can extract separately	07 - Regex
groupby	Split rows into groups, then aggregate each	18 - Pandas
Guardrail	Check that runs on input / output and can block it	33 - Agent Frameworks
Guardrails	Limits and checks on inputs, actions and outputs	32 - AI Agents
Guardrails	Input / output checks and policies around the model	38 - AI Security and Responsible AI

H

Term	Meaning	Guide
Hallucination	Confident but false output	26 - LLM Fundamentals
Handoff	One agent passes control to another (OpenAI Agents SDK)	33 - Agent Frameworks
Harness	The code that runs the loop, executes tools, manages context and limits	32 - AI Agents
HCL	The configuration language of Terraform	47 - Terraform
Header	Key-value metadata (auth, content type)	09 - HTTP and APIs
Helm	Package manager for Kubernetes apps (charts)	46 - Kubernetes
HNSW	Popular graph-based ANN index	30 - Embeddings and Vector Databases
Host	AI app using MCP (Claude Code, Claude Desktop, IDE, your app)	34 - MCP (Model Context Protocol)
HPA	Horizontal Pod Autoscaler: scales replicas on metrics	46 - Kubernetes
HTTP method	The action: GET read, POST create, PUT/PATCH update, DELETE remove	40 - FastAPI
hue	Column used to colour groups	22 - Seaborn
Human-in-the-loop (HITL)	A person approves or corrects steps	32 - AI Agents
Hybrid search	Combining vector similarity with keyword (BM25) search	30 - Embeddings and Vector Databases
Hybrid search	Vector + keyword search combined	31 - RAG (Retrieval-Augmented Generation)
Hyperparameter	Setting you choose before training (max_depth)	23 - Scikit-learn

I

Term	Meaning	Guide
Idempotent	Repeating the request has the same effect as doing it once (GET, PUT, DELETE)	09 - HTTP and APIs
Idempotent	Running a job twice has the same effect as once (safe retries)	42 - Redis, Caching and Task Queues
Image	Read-only package / template of an app	43 - Docker
Indentation	Leading spaces that define structure in YAML	08 - YAML, JSON, TOML and .env
Indentation	Spaces at the start of a line that define code blocks	10 - Python Basics
Index	Row labels (default 0, 1, 2, ...)	18 - Pandas
Index	Structure that makes lookups on a column faster	20 - SQL
Indirect injection	Malicious instructions hidden in content the model reads (web page, email, document, tool result)	38 - AI Security and Responsible AI
Inference	Using a trained model to predict (no training)	24 - PyTorch
Inference	Running the model to get output	26 - LLM Fundamentals
Inference server	Program serving a model over HTTP (Ollama, vLLM, llama-server, TGI)	36 - Local and Self-Hosted LLMs
Ingress	HTTP(S) routing from outside to Services	46 - Kubernetes
Instruction tuning	SFT with instruction-following examples	37 - Fine-tuning
IntelliSense	Autocomplete and code understanding	06 - VS Code
Interpreter	A program that reads source code and runs it line by line (python is the Python interpreter)	01 - Core Concepts: Code, Packages, APIs and SDKs
Interpreter	The Python executable VS Code uses to run your code (pick your .venv)	06 - VS Code
Interpreter	The program that runs Python code (python)	10 - Python Basics
Interpreter	The python executable that runs your code	11 - Python Virtual Environment

J

Term	Meaning	Guide
Jailbreak	Tricking a model into ignoring its safety rules	38 - AI Security and Responsible AI
Jinja	The templating language behind {{ variable }}, {% if %} and filters like upper	51 - Project Templates
.jinja suffix	Marks files Copier must render; the suffix is removed in the output	51 - Project Templates
Job	A set of steps that runs on one runner; jobs run in parallel unless linked with needs	44 - GitHub Actions (CI/CD)
Job / task	One unit of background work	42 - Redis, Caching and Task Queues
JOIN	Combine rows from tables by a key	20 - SQL
JSON	The text format most web APIs use for data ({"name": "Ada", "age": 36})	01 - Core Concepts: Code, Packages, APIs and SDKs
JSON	Text format for data sent and received	40 - FastAPI
JSON-RPC	The message format MCP uses	34 - MCP (Model Context Protocol)
JSON Schema	Machine-readable description of the model, generated automatically	13 - Pydantic

K

Term	Meaning	Guide
KDE	Smooth estimate of a distribution	22 - Seaborn
Keep-alive	Reusing one TCP connection for several requests	41 - Uvicorn (ASGI Server)
Kernel	The Python process that runs the cells	16 - Jupyter
Key / value	Name and its data in a mapping	08 - YAML, JSON, TOML and .env
Key / value	Name and stored data (user:42:name -> "Ana")	42 - Redis, Caching and Task Queues
Knowledge cutoff	Date after which the model has no training data	26 - LLM Fundamentals
kubectl	The command-line tool to talk to the cluster	46 - Kubernetes
KV cache	Memory storing attention data for the current context; grows with context length	36 - Local and Self-Hosted LLMs

L

Term	Meaning	Guide
Label / selector	Key-value tags / how objects find each other	46 - Kubernetes
Latency	Time until the (first) response	26 - LLM Fundamentals
Latency, TTFT	Total response time / time to first token	35 - Evals and Observability
Layer	One cached step of an image build	43 - Docker
Layered architecture	Splitting code into routes (HTTP), services (business logic) and repositories (data access)	50 - Project Structure: Python Microservices + Frontend
Lazy frame	A query plan that runs only on .collect()	19 - Polars and DuckDB
Learning rate	Size of each update step	24 - PyTorch
Least privilege	Give only the minimum access needed	38 - AI Security and Responsible AI
Let's Encrypt / certbot	Free certificate authority / tool to get and renew certificates	45 - Nginx, Reverse Proxy and HTTPS
Library	Reusable code you call from your program to do one job (HTTP, dates, math)	01 - Core Concepts: Code, Packages, APIs and SDKs
Library	A package made by others (pandas, requests)	10 - Python Basics
Lifespan	Startup / shutdown events of the app (load models, open pools)	41 - Uvicorn (ASGI Server)
LLM	Large language model that generates text	49 - Azure VM + Linux + Ollama
LLM-as-judge	A model grades outputs using a rubric	35 - Evals and Observability
Local	Named expression to avoid repetition	47 - Terraform
Localhost	"This computer"; http://localhost:8000 is a server running on your own machine	01 - Core Concepts: Code, Packages, APIs and SDKs
Location	Rules for a URL path inside a server block	45 - Nginx, Reverse Proxy and HTTPS
Lock file	A file recording the exact version of every installed package (uv.lock), so installs are repeatable	01 - Core Concepts: Code, Packages, APIs and SDKs
Logits	Raw output scores before softmax	25 - Hugging Face
LoRA / QLoRA	Low-rank adapters / LoRA on a 4-bit quantized base model	37 - Fine-tuning
Loss	Number measuring how wrong the predictions are	24 - PyTorch

M

Term	Meaning	Guide
Magic command	Jupyter helper starting with % or %% (%timeit)	16 - Jupyter
Managed identity	An identity Azure gives your app so it can access other resources without passwords	48 - Azure
Match	A piece of text the pattern fits	07 - Regex
Matrix	Run the same job for several versions / OSes	44 - GitHub Actions (CI/CD)
max_tokens	Hard cap on output tokens for this response	27 - LLM APIs
MCP Inspector	Developer tool to test servers interactively	34 - MCP (Model Context Protocol)
Memory (short / long term)	Current context window / stored knowledge across sessions	32 - AI Agents
Merge	Combine the changes of two branches	05 - Git and GitHub
Metacharacter	A symbol with special meaning (. * + ? ^ $)	07 - Regex
Metadata / payload	Extra fields stored with each vector (source, date, user) for filtering	30 - Embeddings and Vector Databases
Method (verb)	What to do: GET, POST, PUT, PATCH, DELETE	09 - HTTP and APIs
Microservice	A small, separately deployable service that owns one business capability and its data	50 - Project Structure: Python Microservices + Frontend
Mock / fake / stub	A stand-in for a real dependency (API, database, LLM)	15 - pytest
Model	A class inheriting BaseModel that defines fields and types	13 - Pydantic
Model card	README of a model: purpose, licence, limitations	25 - Hugging Face
Model / estimator	An algorithm object with fit and predict	23 - Scikit-learn
Model Hub	Website hosting models, datasets and Spaces	25 - Hugging Face
Model ID	Exact model string, e.g. claude-opus-5	27 - LLM APIs
Model / module	A network: layers + a forward method (nn.Module)	24 - PyTorch
Modular monolith	One deployable app split internally into well separated modules; often the better first step	50 - Project Structure: Python Microservices + Frontend
Module	One Python file you can import	01 - Core Concepts: Code, Packages, APIs and SDKs
Module	Reusable group of resources (like a function)	47 - Terraform
Module / package	A .py file / a folder of modules you can import	10 - Python Basics
Monkeypatch	Temporarily replace an attribute or env var during a test	15 - pytest
Monorepo	One Git repository containing several services and apps	50 - Project Structure: Python Microservices + Frontend
Multi-agent	Several agents with roles (orchestrator, workers, reviewers)	32 - AI Agents
Multimodal	Can take images / PDFs / audio as input	26 - LLM Fundamentals

N

Term	Meaning	Guide
Namespace	Folder-like isolation for objects	46 - Kubernetes
NaN	Missing value	18 - Pandas
ndarray	NumPy's N-dimensional array	17 - NumPy
Nearest neighbours (kNN)	The k most similar vectors	30 - Embeddings and Vector Databases
Nesting	Objects / lists inside other objects / lists	08 - YAML, JSON, TOML and .env
Node	A machine (VM) that runs pods	46 - Kubernetes
Normalisation	Scaling vectors to length 1 (then dot product = cosine)	30 - Embeddings and Vector Databases
Notebook	The .ipynb document with cells	16 - Jupyter
NSG	Network Security Group: firewall rules for the VM	49 - Azure VM + Linux + Ollama

O

Term	Meaning	Guide
Offline / online eval	On a fixed dataset before release / on live traffic	35 - Evals and Observability
Offloading	Keeping some layers on CPU RAM when VRAM is too small (slower)	36 - Local and Self-Hosted LLMs
OIDC	Keyless login from GitHub to a cloud (no stored cloud passwords)	44 - GitHub Actions (CI/CD)
OLAP	Analytical queries over many rows (DuckDB) vs OLTP transactions (Postgres)	19 - Polars and DuckDB
OpenAI-compatible API	Same endpoints as OpenAI (/v1/chat/completions), so OpenAI clients work	36 - Local and Self-Hosted LLMs
Open-weight model	Model whose weights can be downloaded	36 - Local and Self-Hosted LLMs
Optimizer	Algorithm that updates weights (SGD, Adam, AdamW)	24 - PyTorch
Overfitting	Model memorises training data and fails on new data	23 - Scikit-learn
Overfitting	Great on training data, poor on new data	24 - PyTorch
Overfitting	Memorises training examples, worse on new inputs	37 - Fine-tuning

P

Term	Meaning	Guide
Package	A bundle of modules with a name and version, installed with a package manager (requests, anthropic)	01 - Core Concepts: Code, Packages, APIs and SDKs
Package index / registry	The online store of packages (PyPI for Python, npm for JavaScript)	01 - Core Concepts: Code, Packages, APIs and SDKs
Package manager	A tool that downloads and installs packages and their dependencies (uv, pip, npm)	01 - Core Concepts: Code, Packages, APIs and SDKs
Package manager	Installs software from trusted repositories (apt on Ubuntu)	04 - Linux
Pairwise comparison	Judge picks the better of two outputs	35 - Evals and Observability
Palette	Set of colours	22 - Seaborn
Parallelism	Many tasks running at the exact same time on several cores	14 - Async Python
Parallel tool calls	Several tool_use blocks in one response	29 - Tool Use (Function Calling)
Parameters (7B, 70B)	Number of weights, in billions; bigger = smarter but heavier	36 - Local and Self-Hosted LLMs
Parameters / weights	The learnable numbers inside the model	24 - PyTorch
Parameters / weights	Learned numbers in the model (billions)	26 - LLM Fundamentals
Parametrize	Run the same test with many inputs	15 - pytest
Parquet	Compressed columnar file format (the standard for analytics)	19 - Polars and DuckDB
Pass@k	Share of tasks solved in at least one of k attempts	35 - Evals and Observability
Path	Location of a file or folder (D:\Projects\app)	03 - Terminal and PowerShell
PATH (env var)	List of folders where the shell looks for programs	03 - Terminal and PowerShell
Pattern	The regex itself, e.g. \d+	07 - Regex
PEFT	Parameter-efficient fine-tuning (train a small number of extra weights)	37 - Fine-tuning
Permissions	Who may read, write or execute each file	04 - Linux
PII	Personally identifiable information	38 - AI Security and Responsible AI
pip	Package installer for Python	11 - Python Virtual Environment
Pipeline	Passing output to the next command with \|	03 - Terminal and PowerShell
Pipeline	Preprocessing steps + model as one object	23 - Scikit-learn
Pipeline	One-line helper for a task	25 - Hugging Face
pip / uv	Tools to install packages	10 - Python Basics
Placeholder	A {{ ... }} expression replaced by an answer when the template is rendered	51 - Project Templates
Plan / apply / destroy	Preview / execute / remove changes	47 - Terraform
Planning	Making a step list before acting	32 - AI Agents
Pod	Smallest unit: one (or a few tightly coupled) containers with shared network	46 - Kubernetes
Port 80 / 443	HTTP / HTTPS	45 - Nginx, Reverse Proxy and HTTPS
Port mapping	Connect a host port to a container port (-p 8000:8000)	43 - Docker
Predicate pushdown	Filtering while reading, so less data is loaded	19 - Polars and DuckDB
Preference tuning (DPO, ORPO, RLHF)	Training on "better vs worse" answer pairs	37 - Fine-tuning
Pretraining	Learning to predict text on a huge corpus	26 - LLM Fundamentals
Primary key	Unique ID of each row	20 - SQL
Probe	Health check (liveness, readiness, startup)	46 - Kubernetes
Producer	Code that enqueues jobs (your API)	42 - Redis, Caching and Task Queues
Projection pushdown	Reading only the needed columns	19 - Polars and DuckDB
Project template	A reusable starting point for new projects or parts of projects	51 - Project Templates
Prompt	Everything you send: system instructions, messages, documents	26 - LLM Fundamentals
Prompt	Reusable template (user-controlled, often shown as slash commands)	34 - MCP (Model Context Protocol)
Prompt caching	Provider reuses a repeated prompt prefix: cheaper and faster	27 - LLM APIs
Prompt chaining	Splitting a task into several prompts, output of one feeds the next	28 - Prompt Engineering
Prompt injection	Untrusted text trying to override your instructions (38)	28 - Prompt Engineering
Prompt injection	Input that overrides or hijacks the developer's instructions	38 - AI Security and Responsible AI
Prompt template	Prompt with placeholders filled at runtime	28 - Prompt Engineering
Provider	Plugin that talks to a platform's API (azurerm, aws, kubernetes)	47 - Terraform
Proxy headers	X-Forwarded-For / X-Forwarded-Proto set by a reverse proxy	41 - Uvicorn (ASGI Server)
Pub/Sub	Publish messages to channels; subscribers receive them live	42 - Redis, Caching and Task Queues
Pull request (PR)	A GitHub request to merge a branch, with review	05 - Git and GitHub
Push / pull	Upload / download commits	05 - Git and GitHub
Pydantic model	Class that defines and validates data shape	40 - FastAPI
PyPI	The Python Package Index where libraries are published	10 - Python Basics
pyplot (plt)	The quick, state-based interface	21 - Matplotlib
pyproject.toml	Project file: name, Python version, dependencies, tool settings	12 - uv
.python-version	Which Python version this project uses	12 - uv

Q

Term	Meaning	Guide
Q4_K_M, Q5_K_M, Q8_0	Common GGUF quantization levels (bits + method)	36 - Local and Self-Hosted LLMs
Quantifier	How many times something repeats (+, {3})	07 - Regex
Quantization	Storing weights with fewer bits (8, 5, 4 ...) to save memory	36 - Local and Self-Hosted LLMs
Query	A SELECT statement that reads data	20 - SQL
Query string	?key=value parameters in the URL	09 - HTTP and APIs

R

Term	Meaning	Guide
Rate limit	Max requests allowed per time window	09 - HTTP and APIs
Rate limit	Max requests / tokens per minute for your account	27 - LLM APIs
RBAC	Role-based access control: who can do what, on which scope	48 - Azure
ReAct	Pattern: Reason -> Act -> Observe, repeated	32 - AI Agents
Reasoning / thinking	Model spends tokens thinking before answering	26 - LLM Fundamentals
Red teaming	Deliberately attacking your own system to find weaknesses	38 - AI Security and Responsible AI
Reference answer	Known good answer to compare against	35 - Evals and Observability
Reflection	Agent reviews its own output and improves it	32 - AI Agents
Region	Physical data-centre location (swedencentral, westeurope, northeurope)	48 - Azure
Registry	Storage for images (Docker Hub, Azure Container Registry)	43 - Docker
Regression	Something that worked before and now fails	35 - Evals and Observability
Regression test	Test that reproduces a fixed bug so it never returns	15 - pytest
Reload	Restart automatically on code changes (development only)	41 - Uvicorn (ASGI Server)
Remote / origin	The copy of the repo on a server (GitHub)	05 - Git and GitHub
Render	Turning Markdown symbols into formatted output	02 - Markdown
ReplicaSet	Created by a Deployment to maintain the pod count	46 - Kubernetes
Repository pattern	A class that hides database queries behind simple methods like add and get	50 - Project Structure: Python Microservices + Frontend
Repository (repo)	A project folder tracked by Git (history lives in .git/)	05 - Git and GitHub
Request ID	An ID attached to a request and passed between services so logs can be joined	50 - Project Structure: Python Microservices + Frontend
Request / response	The message you send to an API and the message it sends back	01 - Core Concepts: Code, Packages, APIs and SDKs
requirements.txt	Text file listing the project's packages and versions	11 - Python Virtual Environment
Reranker	Model that re-scores retrieved chunks more precisely	31 - RAG (Retrieval-Augmented Generation)
Rerun (Streamlit)	Script executes again after each user interaction	39 - AI User Interfaces (Streamlit, Gradio, Chainlit)
Resolve	Work out a set of versions that are compatible with each other	12 - uv
Resource	Readable data identified by a URI (app-controlled)	34 - MCP (Model Context Protocol)
Resource	One infrastructure object to manage (azurerm_storage_account)	47 - Terraform
Resource	One service instance: VM, storage account, web app ...	48 - Azure
Resource group	Folder in Azure that holds related resources	49 - Azure VM + Linux + Ollama
Resource group (RG)	Container for related resources; delete the RG = delete everything in it	48 - Azure
Resource provider	Azure service namespace that must be registered (Microsoft.App)	48 - Azure
REST	Style of API built around resources and HTTP methods	09 - HTTP and APIs
Result backend	Where job results / status are stored	42 - Redis, Caching and Task Queues
Retriever	Component that finds relevant chunks for a query	31 - RAG (Retrieval-Augmented Generation)
Retriever / query engine	Component that fetches documents for RAG	33 - Agent Frameworks
Reverse proxy	Server forwarding client requests to backend apps	45 - Nginx, Reverse Proxy and HTTPS
root / sudo	The administrator account / run one command as administrator	04 - Linux
Rubric	Explicit criteria and scale for grading	35 - Evals and Observability
Runner	The machine executing a job (GitHub-hosted or self-hosted)	44 - GitHub Actions (CI/CD)
Runtime	Everything a program needs while it runs: the interpreter, installed packages, environment variables	01 - Core Concepts: Code, Packages, APIs and SDKs

S

Term	Meaning	Guide
safetensors	Safe, fast file format for weights	25 - Hugging Face
Scaffolding	Generating the initial files and folders of a project from a template	51 - Project Templates
Schema	Rules describing valid structure (JSON Schema, Pydantic model)	08 - YAML, JSON, TOML and .env
Script	A .py file you run	10 - Python Basics
SDK	Software development kit: the official package that makes an API easy to use from one language	01 - Core Concepts: Code, Packages, APIs and SDKs
Secret	Encrypted value (API key) available to workflows	44 - GitHub Actions (CI/CD)
Secrets	API keys provided to the app securely, not in code	39 - AI User Interfaces (Streamlit, Gradio, Chainlit)
Semaphore	A limit on how many tasks may run a section at once	14 - Async Python
Serialization	Turning a model back into a dict / JSON	13 - Pydantic
Serialize / dump	Python object -> text (json.dumps)	08 - YAML, JSON, TOML and .env
Series	One column (or row) with an index	18 - Pandas
Server	The program that receives requests and answers them	01 - Core Concepts: Code, Packages, APIs and SDKs
Server	Program exposing tools / resources / prompts	34 - MCP (Model Context Protocol)
Server block	Nginx config for one site / domain	45 - Nginx, Reverse Proxy and HTTPS
Server tools	Run by the provider (web search, code execution)	29 - Tool Use (Function Calling)
Service	Stable network name / IP that load-balances to pods	46 - Kubernetes
Service principal	An identity for automation / CI pipelines	48 - Azure
Session	Stored conversation state for an agent	33 - Agent Frameworks
Session state	Per-user memory that survives reruns	39 - AI User Interfaces (Streamlit, Gradio, Chainlit)
SFT	Supervised fine-tuning on (input, ideal output) examples	37 - Fine-tuning
Shape	Size of each dimension, e.g. (3, 4) = 3 rows, 4 columns	17 - NumPy
Shell	Program that interprets commands (PowerShell, CMD, Bash)	03 - Terminal and PowerShell
SKU / tier	Size and price level of a resource (Basic, Standard, B1, S0)	48 - Azure
Source code	The text files you write (app.py) that describe what a program should do	01 - Core Concepts: Code, Packages, APIs and SDKs
Space	Hosted demo app (Gradio / Streamlit)	25 - Hugging Face
SSE	Server-Sent Events: server streams chunks over one response (LLM streaming)	09 - HTTP and APIs
SSH	Secure remote login to another machine	04 - Linux
SSH key	Private / public key pair used instead of a password	49 - Azure VM + Linux + Ollama
SSH tunnel	Forwarding a local port through SSH to a port on the VM	49 - Azure VM + Linux + Ollama
Standard library	The modules that come with Python itself (json, pathlib, datetime)	01 - Core Concepts: Code, Packages, APIs and SDKs
State	Data passed between steps (messages, intermediate results)	33 - Agent Frameworks
State	File recording managed resources and their IDs	47 - Terraform
Status code	3-digit result: 2xx ok, 4xx client error, 5xx server error	09 - HTTP and APIs
Status code	Result number: 200 OK, 404 not found, 422 invalid input	40 - FastAPI
Step	One command (run) or one reusable action (uses)	44 - GitHub Actions (CI/CD)
Stop reason	Why generation ended	27 - LLM APIs
Streaming	Receive tokens as they are generated (SSE)	27 - LLM APIs
Streaming	Showing tokens as they arrive	39 - AI User Interfaces (Streamlit, Gradio, Chainlit)
Strict mode	No coercion: types must match exactly	13 - Pydantic
Strict tool use	Guarantees arguments match the schema exactly	29 - Tool Use (Function Calling)
Structured output	Response guaranteed to match a JSON schema	27 - LLM APIs
Sub-agent	Agent started by another agent for a sub-task, with its own context	32 - AI Agents
Subscription	Billing unit with its own limits and permissions	48 - Azure
Sync	Make .venv match the lock file exactly	12 - uv
systemd / service	Starts and supervises background programs (web server, Ollama)	04 - Linux
systemd service	Keeps your app running and restarts it on failure / reboot	45 - Nginx, Reverse Proxy and HTTPS
System prompt	Standing instructions for the whole conversation	28 - Prompt Engineering

T

Term	Meaning	Guide
Table / row / column	Data as a grid: records and fields	20 - SQL
Target (y)	The column to predict	23 - Scikit-learn
Task	A coroutine scheduled to run concurrently (asyncio.create_task)	14 - Async Python
Task	What a model does: text-classification, summarization, text-generation ...	25 - Hugging Face
Temperature	Randomness of token choice	26 - LLM Fundamentals
Template version	A Git tag on the template repository (for example v1.2.0) that copier update moves between	51 - Project Templates
Tenant	Your organisation's directory (Microsoft Entra ID)	48 - Azure
Tensor	N-dimensional array (like NumPy) that can live on CPU or GPU	24 - PyTorch
Terminal / shell	A text window where you type commands to run programs	01 - Core Concepts: Code, Packages, APIs and SDKs
Test function	def test_something(): with assert statements	15 - pytest
TLS / SSL certificate	Proves the domain identity and enables encryption	45 - Nginx, Reverse Proxy and HTTPS
Token	Chunk of text (word piece) the model reads and writes; ~4 characters of English	26 - LLM Fundamentals
Tokenizer	Converts text to token IDs and back	25 - Hugging Face
Tokens per second (tok/s)	Generation speed	36 - Local and Self-Hosted LLMs
Tool	A command-line program (ruff, black) installed separately from projects	12 - uv
Tool	A function the model may call, described by name + description + input schema	29 - Tool Use (Function Calling)
Tool	A function the agent can call (29)	32 - AI Agents
Tool	Callable function (model-controlled)	34 - MCP (Model Context Protocol)
tool_choice	Whether / which tool the model must use	29 - Tool Use (Function Calling)
Tool definition	The JSON description you send in tools=[...]	29 - Tool Use (Function Calling)
Tool loop / agentic loop	Repeat: model -> tools -> model until no more tool calls	29 - Tool Use (Function Calling)
tool_result block	Your answer, sent back with the matching tool_use_id	29 - Tool Use (Function Calling)
Tool runner	SDK helper that runs the loop for you	29 - Tool Use (Function Calling)
tool_use block	The model's request: tool name, input arguments and an id	29 - Tool Use (Function Calling)
Top-k	Number of chunks retrieved	31 - RAG (Retrieval-Augmented Generation)
Trace / span	Record of one request / of one step inside it	35 - Evals and Observability
Training / test set	Data to learn from / data held back to check performance	23 - Scikit-learn
Transitive dependency	A package your dependencies need (numpy for pandas)	12 - uv
Transport	How messages travel: stdio (local process) or Streamable HTTP (remote server)	34 - MCP (Model Context Protocol)
TTL / expiry	Seconds until Redis deletes a key automatically	42 - Redis, Caching and Task Queues

U

Term	Meaning	Guide
Upstream / backend	The app behind the proxy	45 - Nginx, Reverse Proxy and HTTPS
Usage	Input / output / cached token counts	27 - LLM APIs
User prompt	The specific request / input for this turn	28 - Prompt Engineering
uv.lock	Exact versions of every package; commit it to Git	12 - uv
uvloop / httptools	Faster event loop and HTTP parser (included in uvicorn[standard])	41 - Uvicorn (ASGI Server)
uv workspace	Several Python packages in one repository sharing one uv.lock and one virtual environment	50 - Project Structure: Python Microservices + Frontend

V

Term	Meaning	Guide
Validation	Checking and converting input data	13 - Pydantic
Validator	Your own function that checks or transforms a field	13 - Pydantic
Variable / output	Input parameter / value exported after apply	47 - Terraform
Vectorisation	Applying an operation to a whole array at once	17 - NumPy
Vectorised operation	Works on a whole column at once, no loop	18 - Pandas
venv	Built-in Python module that creates environments	11 - Python Virtual Environment
.venv	The environment folder in your project	11 - Python Virtual Environment
Version / semantic versioning	A package's release number, MAJOR.MINOR.PATCH; a MAJOR change may break your code	01 - Core Concepts: Code, Packages, APIs and SDKs
Virtual environment	A private folder of packages for one project, so projects do not conflict	01 - Core Concepts: Code, Packages, APIs and SDKs
VM size	CPU / RAM / GPU combination you rent (e.g. Standard_D2s_v5)	49 - Azure VM + Linux + Ollama
Volume	Persistent storage that survives container removal	43 - Docker
Volume / PVC	Storage mounted into pods / a request for persistent storage	46 - Kubernetes
VRAM	GPU memory; the main limit for GPU inference	36 - Local and Self-Hosted LLMs

W

Term	Meaning	Guide
Web API	An API reached over HTTP, usually with JSON requests and responses	01 - Core Concepts: Code, Packages, APIs and SDKs
Webhook	The server calls YOUR URL when something happens	09 - HTTP and APIs
Widget	UI element (button, text input, file uploader)	39 - AI User Interfaces (Streamlit, Gradio, Chainlit)
Worker	Separate process running the app; one per CPU core is a common start	41 - Uvicorn (ASGI Server)
Worker / consumer	Process that runs jobs	42 - Redis, Caching and Task Queues
Workflow	Fixed, code-defined sequence of LLM calls	32 - AI Agents
Workflow	A YAML file describing automation	44 - GitHub Actions (CI/CD)
Working directory	The folder the terminal is currently "in"	03 - Terminal and PowerShell
Workspace	The folder (project) you have open	06 - VS Code
Workspace member	One package inside a uv workspace (a service or a shared library)	50 - Project Structure: Python Microservices + Frontend
WSGI	Older sync interface (Flask, classic Django)	41 - Uvicorn (ASGI Server)

Z

Term	Meaning	Guide
Zero-shot	Instructions only, no examples	28 - Prompt Engineering

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