AI agents are the biggest shift in how we build software since the API. For years we wrote programs that did exactly what we told them, step by step. An AI agent is different: you give it a goal, a set of tools, and the freedom to decide how to reach that goal. It plans, acts, observes the result, and tries again until the job is done. This guide breaks down what an AI agent actually is, how one works under the hood, and how to build a reliable one without getting burned. From Chatbo...