# Context window

How much text the model can hold at once. When it fills up, the oldest material falls out.

Also called: context window, context.

## Covered in these lessons

- [What the agent actually does](https://zero2vibecode.com/learn/vibe-coding-101/0-2-what-the-agent-actually-does)
- [Gemini CLI and the large-context bet](https://zero2vibecode.com/learn/ai-coding-tools/1-2-gemini-cli-and-large-context)
- [The context window, and why long sessions drift](https://zero2vibecode.com/learn/claude-code/1-3-context-window-drift)

Source: https://zero2vibecode.com/glossary/context-window