AI agent
An AI system that does more than answer: it can pursue a goal over several steps, use tools and services, and take actions such as booking, buying or sending, often with little supervision.
An ordinary chatbot waits for a question and replies. An agent is given a goal, such as "renew this registration" or "find the cheapest option and pay for it", and then works through the steps itself: searching, filling in forms, calling other software, and sometimes spending from a small budget.
Agents can also work with other agents. Most of today's agents act for a person or an organisation and within limits that someone sets, which is why the questions of permission, accountability and trust matter as much as the technology.