context window

Definition

An LLM's context window is the hard token-count limit on the prompt-plus-completion it can process in a single request. Sonnet 4.5 and similar 2025-era models offer 200K-1M token windows; Gemini stretches to 2M. Bigger windows enable RAG over more docs and longer agent transcripts without compaction, at the cost of higher per-call latency and price.

When to use

See also

• LLM — Large Language Model — a transformer-based model trained on internet-scale text to generate and reason.
• RAG — Retrieval-Augmented Generation — fetch relevant documents at query time and feed them to the LLM as context.