AI Dictionary
OPEN AI DICTIONARY

From tokens to agents, the AI dictionary.

LLM, RAG, MCP, embedding, fine-tuning… The most-used concepts of modern AI — plain language, real-world examples, and clean illustrations.

FundamentalsAI · ML · NNVectorsEmbeddingLLMTransformerPromptingCoT · Few-shotRAGSearchAgentsMCP · ToolsAIDICTIONARY

Featured terms

The most searched, most misunderstood concepts in modern AI.

ARTIFICIAL INTELLIGENCEMACHINE LEARNINGDEEP LEARNINGeach contains the next
BeginnerFundamentals

Artificial Intelligence

The broad field of building machines that mimic human-like learning, reasoning, and decision-making.

LEARNING FROM DATAyxdata pointslearned functionthe model finds the rule that fits the examples
BeginnerFundamentals

Machine Learning

Letting computers learn patterns from data instead of being explicitly programmed.

promptINPUTLLMbillions of paramsNEXT-TOKEN PREDICTOROUTPUT
BeginnerLLM & Language Models

LLM

A massive AI model trained on huge text corpora that learns to predict the next token and can hold conversations.

SELF-ATTENTION ARCHITECTUREEncoderSelf-AttentionFeed-ForwardAdd & NormDecoderCross-AttentionFeed-ForwardAdd & Normattentionevery word can look at every other word
AdvancedLLM & Language Models

Transformer

The neural-network architecture behind modern LLMs that learns how much each word should attend to every other word.

WORD → MEANING-VECTOR"king"EMBEDDINGMODELVECTOR · 1536 DIM[0.21, -0.45, 0.78,0.12, -0.33, 0.66, …]meaning becomes math: "king − man + woman ≈ queen"
IntermediateVectors

Embedding

A vector representation that captures the meaning of a piece of text, image, or audio.

RETRIEVAL-AUGMENTED GENERATION1QUERYuser asks2RETRIEVEvector DB3AUGMENT+ context4GENERATELLM answersadds fresh, private knowledge without retraining the model
IntermediateRAG & Search

RAG

Query → document retrieval → LLM context injection → answer generation.

MODEL CONTEXT PROTOCOL · ANTHROPIC OPEN STANDARDLLM HOSTClaude · Cursor · …MCPuniversal protocolFilesystemPostgresGitHubSlackCalendarplug any data source into any AI app — once, in a standard way
AdvancedAgents & Protocols

MCP

An open protocol that lets AI applications connect to external data sources and tools in a standardized way.

LLM + TOOLS = AGENTAGENTplan + actsearchcodeAPIfilesloops until the goal is met, calling tools as needed
AdvancedAgents & Protocols

AI Agent

An autonomous system that uses an LLM as its brain to call tools, plan, and reach a goal step by step.

VAGUE"Write somethingabout databases."OUTPUT"Databases are systemsused to store data…"vague answerPRECISE"Compare Postgres vs SQLitefor an offline mobile app.3 bullets, with a verdict."OUTPUT• Postgres: server-required…• SQLite: file-based, ideal…• Verdict: SQLite. ✓same model, dramatically different output
BeginnerPrompting

Prompt

The input text you give an LLM — its quality largely determines the quality of the answer.

Calculators & tools

From token cost to GPU sizing — practical answers to the questions you face when shipping AI.