Reference · Glossary
Context window
The maximum amount of text (measured in **tokens**) a model can read and remember **in one conversation turn**.
When to use
Planning long documents, multi-file code help, or chat history — if input is too long, the model drops or forgets middle parts.
When not to
Don't confuse with long-term memory products; the context window is the working desk, not a filing cabinet.
Example
A 128K-token window fits a short book chapter plus your questions. A 500-page PDF may need chunking or RAG instead.