Autoloading is the magic that lets us use classes without needing to require or include the file that holds them first. An autoloader has a tricky job: given any class name, it needs to know the exact location of the file that holds that class. In many modern projects, including ours, Composer handles this for us, and there are two pieces to understanding how it figures out what file a class lives in. In this lesson we're going to get an overview of how directory structures and namespaces make autoloading work.