AI buzzword dictionary

What is Context window?

The maximum amount of text a model can take into account at one time.

What this actually means

Everything in a conversation — your messages, the AI's replies and any documents you paste — has to fit inside the context window, measured in tokens.

When a conversation grows past that limit, earlier parts may be dropped or summarised, and the AI can appear to 'forget' them.

Example

You paste a long contract and ask about clause 40. If the document is too long for the window, the tool may miss the clause entirely.

Where you may meet it

Long chats, document summaries, and tools that advertise how many pages they can read.

Related terms and lessons

TokenA small chunk of text — often part of a word — that language models read and write.RAG (retrieval-augmented generation)A method where an AI first looks up relevant documents, then uses them to write its answer.How to write a better AI promptMost disappointing AI answers come from vague instructions. This short lesson shows a simple checklist you can use with any chat assistant.Using AI for reports and researchAI is useful for structure, summaries and first drafts. It is weakest at facts and sources, so research still needs checking.

Last reviewed: 25 September 2026