You paste a long article into a chat and ask Claude for the key points. What is Claude actually doing?

The principle — Claude works from the material in front of it, so what you supply is what it reasons over.

Why the key is correct — Anthropic lists summarising long articles, documents and even books as a core use. The text you pasted is the input, and the summary is generated from it rather than retrieved.

Why the others are wrong — nothing is fetched from the web unless you turn web search on. Summarising is not truncation; it restates substance in fewer words. And pasting something into your chat does not publish it to anyone else.

Remember this — give Claude the material and it works from that. Describing a document is never as good as supplying it.

Sources — Anthropic's guide to what Claude can be used for.