The maximum amount of text an AI model can process in a single interaction, measured in tokens.
The context window is an LLM's working memory — the total amount of text it can "see" at once, including the conversation history, system instructions, and any retrieved documents. It is measured in tokens, where one token roughly equals 3-4 English characters.
Context window sizes have grown dramatically. Early models had 4K tokens (about 3,000 words). Modern models like Claude offer 200K tokens (about 150,000 words — roughly a full novel). This expansion fundamentally changes what AI agents can do: they can analyze entire codebases, process lengthy documents, and maintain coherent long conversations.
For AI agent systems, context window size determines how much information an agent can work with simultaneously. A larger context window means the agent can see more of your codebase, understand more of the project history, and make better-informed decisions. At Agentik {OS}, we use context management strategies — RAG, summarization, and selective retrieval — to ensure our agents always have the most relevant information within their context window, regardless of project size.
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