Glossary

25 terms. No jargon. Real numbers. Every explanation grounded in data from sourc.dev.

25 Total terms

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Token You already know what a token is. You just don't know you know.

Context window Think of it as the model's desk.

Input price Input price is what you pay to send text to a model.

Output price Output price is what you pay for the model's response.

What does "per 1M tokens" mean It is a pricing unit. Like kilowatt-hours for electricity, or per-kilometre for fuel. A way to compare costs at a standa…

Function calling You have used a phone menu. Press 1 for billing. Press 2 for support. Press 3 for account. The menu does not answer your…

Vision / image input Before vision, you described things to the model. Now you can show it.

Streaming You send a request. You wait. Nothing happens. Five seconds. Eight seconds. Twelve seconds. A full response appears at o…

MCP — Model Context Protocol For most of AI's recent history, every tool was an island.

Free tier A free tier is a usage allowance that costs nothing. Most major model providers offer one — a number of requests, tokens…

EU data residency Think of it as keeping your filing cabinet inside the building.

MMLU MMLU stands for Massive Multitask Language Understanding. It is a benchmark — a standardised test for language models — …

HumanEval HumanEval is a coding benchmark. 164 programming problems, each with a function signature, a docstring describing what t…

API Every time you check the weather on your phone, your phone did not go outside.

REST API Imagine a restaurant.

API key It is a password. A long one, impossible to guess, that identifies your application when it calls an API.

SDK SDK stands for Software Development Kit. It is a library — code someone else wrote — that wraps an API and makes it easi…

Rate limit A rate limit is a ceiling on how many requests you can make in a given time window.

LLM LLM stands for Large Language Model. The name tells you three things: it works with language, the model is large, and it…

Open weights When a model is released with open weights, the trained model itself is publicly available. You can download it, run it …

Hallucination A language model hallucinates when it generates text that is confident, fluent, and wrong.

RAG Think of it as the difference between an open-book exam and a closed-book exam.

Fine-tuning The difference between hiring someone already trained and training someone yourself.

Latency Receives your request → processes tokens → generates a response → sends it.

What does 70B mean When you see Llama 3.3 70B, the 70B is the parameter count. 70 billion parameters. It is not a version number. It is not…