An AI agent is a system that not only generates output but also takes actions to achieve goals (e.g. planning tasks, invoking tools) with limited supervision. In other words, it can “act” in an environment, not just chat. A recent example is ChatGPT’s new agent mode, which can plan trips, run code, and interact with apps on your behalf. AI agents build on large language models by adding workflow logic and tool use, heralding a shift from passive Q&A toward proactive AI assistants.