An AI agent is a program that carries out a task by itself, within a frame people set in advance. Setting up that frame comes first. The person who sets up the agent connects it to the software it may use. That person can be a developer writing code, or a user adding connections in a settings screen. They also write the instructions and limits the agent must follow: which actions it may take, and which cases must stop it and go to someone else, such as a payment above an agreed amount. The user then gives it a goal. From there the agent takes over. It uses a large language model (LLM), the same engine behind AI chat, to decide which steps to take and which tools to use. It carries those steps out itself: it can send an email, update a customer record, edit a web page or search a database. It checks the results, corrects its course and continues until the task is done. When it meets one of those set cases, or fails more times than the limit people set, it stops and hands the work to a person or to another agent set up for that case. Because the agent acts in live systems itself, the access and limits people set decide how useful it is.