📖 The AI Dictionary

Every AI term
explained plainly

No jargon. No math. Just clear definitions of the AI terms you'll actually encounter — from RAG and LoRA to agentic AI, fine-tuning, and MCP. Updated weekly by our editorial team.

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A3 terms
Agentic AI
agents

AI systems that can plan, execute, and self-correct over multi-step tasks autonomously, rather than just answering one question at a time. They use tools, browse the web, and iterate on goals.

Example
A coding agent that reads a bug report, locates the file, writes a fix, runs the tests, and opens a pull request — all without human intervention.
AGI
Artificial General Intelligencecore

A hypothetical AI that can perform any intellectual task a human can, across any domain. Current AI is "narrow" — it's superhuman at chess or coding but useless at unrelated tasks. AGI would generalize.

Example
An AGI could read a medical paper, then turn around and design a bridge, then debug a Linux kernel — at expert level in all three.
Attention
models

The mechanism that lets a transformer model "look at all words at once" and decide which ones matter for predicting the next one. It's why ChatGPT can resolve "it" in long sentences.

Example
In "The cat sat on the mat because it was warm," attention helps the model link "it" → "mat" or "cat" based on context.
B1 term
Batch inference
training

Running many prompts through a model at once instead of one at a time. Cheaper and faster per request, but with higher latency for any individual response.

Example
OpenAI offers a Batch API that's 50% cheaper than real-time — perfect for embedding 1M documents overnight.
C2 terms
Chain of Thought
CoTcore

A prompting technique where you ask the model to "think step by step" before answering. Dramatically improves accuracy on math, logic, and reasoning tasks.

Example
Prompt: "Let's think step by step. First, identify the variables…" — turns a wrong answer into a right one on multi-step problems.
Context window
models

The maximum amount of text (measured in tokens) a model can "see at once." Bigger = it can read more of your codebase, document, or chat history in a single call.

Example
GPT-5 has a 1M token context (~750K words). Claude 4 has 500K. GPT-3.5 had only 4K — a huge limitation back then.
D2 terms
Deep research
agents

An agentic mode where the AI autonomously searches the web for 5–30 minutes, reads dozens of sources, and produces a long, cited report. Pioneered by OpenAI and Google.

Example
"Write a deep research report on Series A funding trends in AI agents in 2025" — returns a 15-page cited document.
Diffusion model
models

The class of AI that powers image generators like Midjourney and Stable Diffusion. It learns to reverse the process of adding noise to an image, gradually "denoising" random pixels into a coherent picture.

Example
Type "a cat astronaut on Mars" — the model starts with TV static and iteratively shapes it into your image.
E1 term
Embeddings
core

A way of representing text (or images, audio) as a list of numbers that captures meaning. Two pieces of text with similar meaning will have similar embeddings.

Example
"Dog" and "puppy" have nearly identical embeddings. "Dog" and "spreadsheet" are far apart. This is how semantic search works.
F1 term
Fine-tuning
training

Taking a pre-trained model and training it further on your own data so it learns your style, domain, or task better. Cheaper than training from scratch.

Example
A law firm fine-tunes GPT-4o on its case archive so the AI writes briefs in the firm's specific voice and citation style.
G1 term
GPT
Generative Pre-trained Transformermodels

OpenAI's family of language models. "Generative" (it creates text), "Pre-trained" (on most of the internet), "Transformer" (the underlying architecture).

Example
GPT-2 (2019), GPT-3 (2020), GPT-4 (2023), GPT-5 (2026) — each generation roughly 10× larger and smarter.
H1 term
Hallucination
core

When an AI confidently states something false. The model isn't lying — it's generating plausible-sounding text based on patterns, and sometimes those patterns produce wrong facts.

Example
Asking GPT-4 about a 2024 court case it didn't see in training — it may invent a fake citation that looks real.
I1 term
Inference
core

When the model is running — generating output for a user query. Different from training, which is when the model learns. Inference is what costs money per API call.

Example
You type a prompt — the model runs inference for ~2 seconds — you get a response. That single call costs $0.0001–$0.10.
L2 terms
LLM
Large Language Modelmodels

A neural network trained on massive amounts of text to predict the next word. The category includes GPT, Claude, Gemini, Llama, etc. "Large" usually means 1B+ parameters.

Example
When you ask ChatGPT a question, an LLM predicts each word one at a time, considering everything that came before.
LoRA
Low-Rank Adaptationtraining

A way to fine-tune a model by adding a small "adapter" instead of retraining the whole thing. 100× cheaper than full fine-tuning, with similar results.

Example
Stable Diffusion users share LoRAs that teach the model specific art styles (e.g. "anime LoRA," "cyberpunk LoRA").
M2 terms
MCP
Model Context Protocolagents

An open standard from Anthropic that lets AI assistants plug into external tools (databases, APIs, file systems) in a uniform way. Think USB-C for AI agents.

Example
Claude Desktop with MCP can query your Postgres database, read your GitHub repos, and edit your local files — all through one protocol.
Multimodal
models

A model that can handle more than one type of input — typically text, images, audio, and video together. GPT-4o, Gemini, and Claude are all multimodal.

Example
Upload a chart screenshot + ask "explain this trend" — multimodal model reads both image and text in one go.
P3 terms
Parameters
models

The "knobs" inside a neural network that get tuned during training. More parameters = more capacity. GPT-3 has 175B parameters. Llama 4 has 405B.

Example
Each parameter is a number. A 70B model = 70 billion numbers. That's why models need GPUs to run.
Pre-training
training

The first, most expensive step of building an AI: feeding it huge amounts of text from the internet so it learns language patterns. Costs millions of dollars in GPU time.

Example
GPT-4 was pre-trained on roughly 13 trillion tokens of text — books, web pages, code repositories.
Prompt engineering
core

The art of writing instructions for an AI so it gives you exactly what you want. Bad prompts → bad outputs. Good prompts → magic.

Example
"Write a poem" → mediocre. "Write a 4-stanza sonnet about coffee in the style of Shakespeare, ABAB rhyme scheme" → great.
R3 terms
RAG
Retrieval-Augmented Generationcore

A technique that lets the AI look up information from a database or document collection before answering, instead of relying only on what it learned in training.

Example
You ask "What's our company's refund policy?" → RAG retrieves the relevant page from your internal docs → AI answers using that.
Reasoning model
models

A class of model (e.g. OpenAI o1, DeepSeek R1) that "thinks" before responding, using extra compute at inference time to work through hard problems step by step.

Example
Standard model: instant answer. Reasoning model: 15-second pause, then a much better answer for math/code/logic tasks.
RLHF
Reinforcement Learning from Human Feedbacktraining

The training step that aligns AI behavior with human preferences. Humans rate model responses; the model learns to produce responses humans prefer.

Example
RLHF is why ChatGPT is polite, helpful, and refuses harmful requests — it was rewarded by humans for that behavior.
T5 terms
Temperature
core

A setting (0–2) that controls how random the output is. Low = deterministic and focused. High = creative and varied. 0.7 is the typical default.

Example
Code generation: use temperature 0 for consistency. Creative writing: use 0.9 for variety.
Test-time compute
models

How much thinking time the model uses when answering. New reasoning models (o1, o3) get smarter by spending more compute at inference, not just at training time.

Example
30 seconds of test-time compute on a math problem can match a 10× larger model running normally. Tradeoff: cost and latency.
Token
core

The basic unit of text an LLM processes. Roughly ¾ of a word in English. "ChatGPT is amazing" → 5 tokens. API pricing is per token.

Example
1M tokens ≈ 750K words ≈ a 1,500-page novel. GPT-4 charges $30 per 1M output tokens.
Tool use
agents

When an AI is allowed to call external functions — search the web, run code, look up a database, send an email. Critical capability for agents.

Example
You ask "what's the weather in Tokyo?" — AI doesn't guess, it calls a weather API and reports back.
Transformer
models

The neural network architecture that powers every modern LLM. Introduced by Google in 2017 ("Attention Is All You Need"). Replaced earlier RNN-based models.

Example
GPT, Claude, Gemini, Llama, Mistral — all transformers. The "T" in GPT stands for Transformer.
V3 terms
Vector database
core

A specialised database for storing and searching embeddings. Lets you find "semantically similar" items quickly — the backbone of RAG, recommendation engines, and semantic search.

Example
Pinecone, Weaviate, Chroma are popular vector DBs. Store 10M document embeddings → find the 5 closest in milliseconds.
Vibe coding
agents

A term coined by Andrej Karpathy for building software by describing it in plain English to an AI agent, accepting whatever it writes without reading the code carefully.

Example
"Build me a Twitter clone with dark mode and a feed" — AI scaffolds the entire app. You test, refine, ship.
Vision-language model
VLMmodels

A model that can see images and produce text. Lets you upload a photo and ask questions about it.

Example
GPT-4V can read a screenshot of your code, identify the bug, and suggest the fix.
Z1 term
Zero-shot
core

Asking the AI to do a task with no examples in the prompt. Modern LLMs are good at this — but few-shot (with examples) usually works better.

Example
Zero-shot: "Translate this to French: hello." Few-shot: "Translate: 'dog'→'chien'. 'cat'→'chat'. Now: 'hello'→"
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