Agent

An agent, in artificial intelligence (AI), is a tool that does not just answer a question but can take a series of actions on its own to complete a goal you set. Given a task, it can plan the steps, use other software and adjust as it goes, rather than waiting for each instruction.

It is like the difference between an assistant who answers when asked and one you can hand a whole errand to and trust to see it through. Agents matter because they can take real work off people's plates, though the more freedom they have to act, the more careful the limits and checks around them need to be.