MPC files...what the heck are they, and what plays them?

Factual Questions
1

pretty much what the thread title asks…how do i open and use mpc files?

2

According to here, you play them with Winamp.

3

Thanks, got it working now…was just confused by seeing a new file type I’d never seen before.

4

So, what exactly is an MPC file, anyway? Is it a variant of MP3?