# Grounding

> Grounding is how Copilot adds relevant content from your work data to your prompt before the model sees it, so answers draw on your actual mail, files and chats.

**Category:** Copilot

**Grounding runs on every prompt, before the model writes a word.** Copilot checks [Microsoft Graph](/glossary#microsoft-graph) for content relevant to your question, using the semantic index to match on meaning. What it finds is appended to your prompt, and only that combined package goes to the model. The model never reads your mailbox directly, and grounding can only surface **what you personally have permission to see**.

That is a real head start: no hunting for a file to paste in first. The catch is that grounding runs fresh each time, so the same vague question can land differently depending on what ranks highest that day. Naming the file, mailbox or time range turns a guess into a lookup. Copilot can also ground answers in current web results; that is [web grounding](/glossary#web-grounding).

## At work

An account manager asks about "the Devlin contract" and gets a thinner answer than expected. The full file sits in a folder she can't access, so grounding never saw it; Copilot worked correctly on a narrower set of files than she assumed.

## Often confused with

Context window. In Claude you load context in yourself and the window has a published size. Copilot builds its context for you through grounding and publishes no [context window](/glossary#context-window) size.

## Related terms

- Microsoft Graph
- Semantic index
- Web grounding
- Context

## See it in a lesson

[Context and grounding](/en/learn/copilot/working-smart/context-and-grounding)

## Further reading

- [How grounding works with a work or school account (Microsoft Support)](https://support.microsoft.com/en-us/topic/how-grounding-works-with-a-work-or-school-account-a3ccafb3-7fd3-4d51-bbd2-4245a7a1ef16): How Copilot grounds answers when you sign in with a work account.
- [Microsoft Copilot architecture and how it works (Microsoft Learn)](https://learn.microsoft.com/en-us/microsoft-365/copilot/microsoft-365-copilot-architecture): How Copilot processes a prompt from start to finish.
- [What information does Copilot use to answer my prompt? (Microsoft Support)](https://support.microsoft.com/en-us/microsoft-365-copilot/what-information-does-copilot-use-to-answer-my-prompt): Which sources Copilot draws on for an answer.

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Last updated: 14/10/2026  
Source: Rollo Academy glossary