Definition
Context window
A context window is the amount of information a model can consider in a single request, usually measured in tokens. It includes the system instructions, user prompt, retrieved documents, conversation history, and any output the model must generate.
Last updated: 25 June 2026
Why it matters
It shapes cost, accuracy, and product design because not everything can be placed in front of the model.
Signals to watch
- Inputs must be shortened
- Retrieved chunks compete for space
- Long conversations lose detail