AI glossary
30 terms you’ll meet when choosing AI tools, each explained in one or two plain sentences, with a link to tools that use it.
What does “AI agent” mean?
An AI system that takes steps on its own toward a goal, such as searching, clicking, writing files or calling other tools, instead of only answering one message. See assistant tools.
What does “AI assistant” mean?
A chat tool, such as ChatGPT, Claude or Gemini, that answers questions, writes and summarises text, and helps with tasks in conversation. See assistant tools.
What does “AI Overview” mean?
The AI-written summary Google shows above some search results, built from pages it links to as sources. See Google’s guide to AI features: developers.google.com
What does “Agent skill” mean?
A folder of instructions (a SKILL.md file plus optional scripts) that teaches an AI agent like Claude Code a repeatable way to do one job.
What does “AEO (answer engine optimization)” mean?
Making a page easy for answer engines to quote: a direct answer near the top, question headings and clear lists or tables.
What does “API” mean?
A way for one program to use another; most AI tools offer an API so developers can build the model into their own apps, usually priced per token. See coding assistant tools.
What does “Context window” mean?
How much text a model can consider at once, measured in tokens. A larger window lets it read longer documents or conversations in one go.
What does “Diffusion model” mean?
The kind of model behind most AI image and video generators: it starts from random noise and removes it step by step until an image matches the prompt. See image tools.
What does “Embedding” mean?
A list of numbers that captures the meaning of a piece of text or an image, so software can find similar items by meaning instead of exact words.
What does “Fine-tuning” mean?
Training an existing model further on your own examples so it follows a specific style, format or task more reliably.
What does “Foundation model” mean?
A large model trained on broad data that other products build on, such as GPT, Claude, Gemini or Llama.
What does “Free plan” mean?
A plan you can use without paying, usually with limits on usage, features or output quality. On Tool Directory AI it is only listed as free when the tool’s own website says so.
What does “GEO (generative engine optimization)” mean?
Making a brand and its pages easy for AI assistants such as ChatGPT, Claude and Perplexity to find, trust and cite in their answers.
What does “Generative AI” mean?
AI that creates new content, such as text, images, audio, video or code, rather than only sorting or predicting from existing data.
What does “Hallucination” mean?
When an AI states something false with confidence, such as an invented fact, quote or source. Check important answers against the original.
What does “Image-to-video” mean?
Turning a still image into a short video clip, often with a prompt describing the motion. See video tools.
What does “Inference” mean?
Running a trained model to get an answer. Most AI pricing is for inference: you pay each time the model reads and writes.
What does “LLM (large language model)” mean?
A model trained on large amounts of text to predict the next word, which lets it write, summarise, translate and answer questions. See assistant tools.
What does “llms.txt” mean?
A short Markdown file at a site’s root that summarises the site for AI assistants and links to its key pages. The proposal: llmstxt.org
What does “MCP (Model Context Protocol)” mean?
An open standard for connecting AI assistants to outside tools and data, such as files, databases or apps, through a common interface. Specification: modelcontextprotocol.io See coding assistant tools.
What does “Multimodal” mean?
A model that works with more than one kind of input or output, for example reading images and text, or turning speech into text.
What does “Open-weight model” mean?
A model whose trained weights are published so anyone can download and run it, such as Llama or Mistral models; the license sets what you may do with it.
What does “Prompt” mean?
The instruction or question you give an AI tool. Clear prompts with context, examples and the format you want get better results.
What does “RAG (retrieval-augmented generation)” mean?
A setup where the AI first looks up relevant documents, such as your files or the web, and then answers using them, which reduces made-up answers. See research tools.
What does “Speech-to-text” mean?
Turning spoken audio into written text, used for transcripts, captions and meeting notes. See audio tools.
What does “Text-to-image” mean?
Creating an image from a written description. See image tools.
What does “Text-to-speech (TTS)” mean?
Turning written text into spoken audio in a synthetic or cloned voice. See audio tools.
What does “Text-to-video” mean?
Creating a video clip from a written description. See video tools.
What does “Token” mean?
The small chunk of text a model reads and writes, often part of a word. Context limits and API prices are counted in tokens.
What does “Vibe coding” mean?
Building software by describing what you want to an AI coding tool and accepting or steering its code, rather than writing most of it by hand. See coding assistant tools.
Written by Vamsi Reddy and Sai Goutham Reddy, updated . Missing a term? Tell us. For checking your own site, try the free AI SEO checker.