What is Copilot Chat used for?

Copilot Chat is a conversational layer over the same models behind Copilot's other features, and GitHub's feature list calls it the chat interface that lets you ask coding-related questions. In practice that means explaining an unfamiliar function, generating unit tests, proposing a fix for the stack trace you just pasted in, or working out why a query is slow. It runs on the GitHub website, in GitHub Mobile, in the Copilot CLI and inside supported editors such as VS Code, JetBrains and Xcode. Because the exchange is a conversation rather than a single shot, the follow-up question is cheap: the previous turn is still in context, so "now do it without the extra allocation" lands.

The other three options describe some other product. Chat does not fetch weather, run a mailbox, or delete files by itself. Even agent mode, which can edit files and run terminal commands, surfaces those actions for your approval instead of acting silently. One caution for code review: GitHub states plainly that the code Chat generates may be incorrect or carry security vulnerabilities, so it is a draft you validate, not output you trust.