# Context window

> The limited space that holds everything Claude is working with right now: your files plus the whole conversation, all measured in tokens.

**Category:** Core concept, Under the hood

**The context window is Claude's working memory.** It holds the files you have shared and the whole back-and-forth of the chat, all measured in [tokens](/glossary#token). It is large, but not endless.

When a long chat fills the window, older parts get squeezed, so detail can slip and answers drift. The fix is simple: **keep chats focused, share lean files, and start fresh when you switch topics.**

## At work

Notice a long chat getting forgetful or repeating itself? That is the window filling up. Start a new chat and paste a short summary to carry the thread over.

## Often confused with

Context. [Context](/glossary#context) is what you put in; the context window is the space that holds it, with a limit.

## Related terms

- Token
- Context
- Chat

## See it in a lesson

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

## Further reading

- [Context windows (Anthropic docs)](https://docs.claude.com/en/docs/build-with-claude/context-windows): How the window works and how big it is.
- [How do usage and length limits work? (Help)](https://support.claude.com/en/articles/11647753-how-do-usage-and-length-limits-work): Why very long chats hit a ceiling.
- [Large language model (Wikipedia)](https://en.wikipedia.org/wiki/Large_language_model): Background on why models have a fixed window.

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Last updated: 24/07/2026  
Source: Rollo Academy glossary