> ## Documentation Index
> Fetch the complete documentation index at: https://docs.voiceflow.com/llms.txt
> Use this file to discover all available pages before exploring further.

# AI terms

> Model, token, context window, RAG, embedding, grounding and hallucination: general industry terms, defined exactly as these docs use them.

General industry terms, defined as they are used in these docs. They are not
Voiceflow-specific, and are here so a page can link to one rather than explain
it again.

| Term               | What it is                                                                                                                                                                                                                                                     |
| ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Model**          | The language model generating a reply. Which one an agent uses is a [behaviour](/documentation/build/behaviour) setting, and the choice affects both quality and credit cost.                                                                                  |
| **LLM**            | Large language model. Used interchangeably with *model* above.                                                                                                                                                                                                 |
| **Token**          | The unit a model reads and writes text in, roughly a word-piece. Usage and cost are measured in tokens, which is why [analytics](/documentation/measure/analytics) reports them.                                                                               |
| **Context window** | How much text a model can consider at once, counted in tokens. Everything the agent sends on a turn competes for the same window.                                                                                                                              |
| **Prompt**         | The text given to a model to produce a reply. In Voiceflow this is assembled from the global prompt, the instructions, and the conversation so far.                                                                                                            |
| **System prompt**  | The instruction layer a model treats as standing orders rather than user input. Voiceflow's [global prompt](/documentation/build/global-prompt) fills this role.                                                                                               |
| **RAG**            | Retrieval-augmented generation. Fetching relevant documents and giving them to the model so the answer is grounded in your content rather than the model's training. This is what the [knowledge base](/documentation/build/querying-the-knowledge-base) does. |
| **Embedding**      | A numeric representation of a piece of text, used to find passages that mean something similar rather than merely sharing words.                                                                                                                               |
| **Chunk**          | One passage a document is split into before it is embedded. Chunking decides what retrieval can return.                                                                                                                                                        |
| **Grounding**      | Constraining an answer to supplied source material, so the model reports rather than invents.                                                                                                                                                                  |
| **Hallucination**  | A fluent, confident answer that is not true. The reason grounding and evaluations matter.                                                                                                                                                                      |
| **Tool calling**   | A model choosing to invoke a tool, with arguments, instead of replying in prose. What makes a playbook agentic.                                                                                                                                                |
| **Temperature**    | How much randomness a model uses when choosing words. Lower is more repeatable, higher more varied.                                                                                                                                                            |
| **MCP**            | Model Context Protocol. An open standard for exposing tools to a model, so the same tool works across clients.                                                                                                                                                 |

<Note>
  Capitalisation carries meaning here. "Agent step" and "Function step" name
  specific steps; the bare words *step* and *tool* stay lowercase.
</Note>