Knowledge tagged “fundamentals”
Agent
A model harnessed with tools, a system prompt and a context window that takes turns with a user: the unit you actually talk to.
Context
The task-relevant information the agent has access to right now, as distinct from the context window and the session.
Context window
Everything the model sees on each model provider request: finite, model-specific, and the only surface through which it perceives anything.
Model
The parameters: a stateless next-token predictor that can't do anything agentic until it is harnessed.
Token
The atomic unit a model reads and writes; context window size, cost and latency are all counted in tokens.