A link through which Claude can search, read and, with your approval, act in another tool such as a drive, a mailbox or a calendar.
Through a connector Claude acts with your permissions in that tool: at most what you may see and change there, and only with the functions the connector allows. So let Claude read a lot but do little on its own, and check under “Customize” and “Connectors” what is connected. With Gmail, Claude asks by default before it sends, replies to or forwards a message.
Example from Basics
In the course's fictional plant shop, Claude uses a connector to find return instructions version C on the shared drive. It does not need to change anything there.
Basics: “Claude bedienen”. In the Werkbank course room, with sign-in.