Since AAC is the audio format of choice for all music sold or encoded using Apple's iTunes software, many people assume Apple has some special right to the format. It doesn't.
The truth is that AAC (Advanced Audio Coding) is just one of many audio standards, and is available on a wide range of non-Apple products. It's arguably a superior format to MP3 because it does a more efficient job of encoding audio. In spite of its advantages, though, the MP3 format is still regarded as the most universally compatible standard for consumer digital audio.
So if you've been thinking your collection of AAC files would only play on an iPod or iPhone, here's a selection of portable audio players that would like to argue otherwise.