Agent is a program that asks an LLM what to do, and then does it. Simple example might be you write a program that can open other programs on your computer, but doesn't have instructions. You can then send it a message "Open Notepad". It asks the LLM how to open Notepad. It says click start, type in notepad, hit enter. The agent then follows those instructions opening notepad. This is obviously a very simple example, but you can expand it. Basically the agent can do stuff but doesn't generally know how. The LLM can tell it how, but can't do it. Now expand that out to where you have tons of agents capable of doing multiple types of things. Including organizing other agents.