<p>From the reading that I have done, Core Audio relies heavily on callbacks (and C++, but that's another story).  </p>

<p>I understand the concept (sort of) of setting up a function that is called by another function repeatedly to accomplish a task.  I just don't understand how they get set up and how they actually work.  Any examples would be appreciated.</p>

Callbacks in C are usually implemented using function pointers and an associated data pointer. You pass your function
```
on_event()
```
and data pointers to a framework function
```
watch_events()
```
(for example). When an event happens, your function is called with your data and some event-specific data.
Callbacks are also used in GUI programming. The
GTK+ tutorial
has a nice section on the
theory of signals and callbacks
.