What is Context Window? Simple Explanation (2026)
AI Glossary
What is Context Window?
Definition: A context window is the maximum amount of text (measured in tokens) that an AI model can process at once. A larger context window means the AI can work with longer documents and maintain longer conversations.
How Does Context Window Work?
The context window includes both your input (prompt, documents, conversation history) and the model’s output. Once the context window is full, the model can’t process additional information. Different models have different context window sizes.
Examples
GPT-4o: 128K tokens (~96K words). Claude 3.5: 200K tokens (~150K words). Gemini 1.5 Pro: 1M tokens (~750K words).
Related Reading
Learn more about how Context Window is used in practice:
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