3. Context Windows and Tokens

The lesson

A token is a small chunk of text. Context window is the model's working memory for the current request.

Long context is useful, but it costs money, time, and memory. Put the highest-value facts first and remove old noise.

For coding, include file names, exact error text, acceptance criteria, and what must not change.

A paralegal splits a long lease into themed blocks, feeding the rent terms, the maintenance clauses and the termination conditions as separate context rather than pasting the whole document.

A hospital clinical coder supplies only the discharge summary and the diagnosis list, removing pages of unrelated observation charts so the request stays focused on the coding question.

A freight forwarding coordinator gives the model the shipment reference, the carrier conditions and the current delay note, leaving older email chains out so the context budget is preserved.

A laboratory scientist trims a procedure review to the method section and the instrument settings, discarding boilerplate that would consume space without adding information.

A software developer pastes only the failing function, the exact error text and the acceptance criteria, avoiding a whole-project dump that would exhaust the context window.

A production engineer chunks a machine manual by inspection type, sending only the lubrication and calibration sections needed for the current question.

A course lecturer summarises a topic in three short blocks, keeping the key facts at the top of the prompt and deleting earlier drafts that no longer matter.

A credit analyst feeds the statement lines that matter plus a short account history, trimming commentary so the model reads the numbers first.

A property manager condenses a building file into a summary plus exact excerpts from the current inspection report instead of attaching the entire history.

A sports journalist gives the model the match summary and two or three direct quotes, keeping the prompt short enough to remain inside working memory.

Check yourself