Today there are dozens of different audio formats. The reason of that I think lies in the attempt to create a better compression scheme. And they achieved amazing results in that. For example, mp3 can squash your song to 1/11 of the original size, still retaining considerable quality. The advantage of mp3 format is also its widespread acceptance. Most audio players including iPods support it.
To compete against mp3 Microsoft introduced WMA. This can also compress audio files with a loss in quality that many people will not distinguish. It’s the second widespread audio format today (thanks to Microsoft’s aggressive promotion).
WAV is another Microsoft’s format, which is sure to be supported by almost all PCs. The shortcoming of WAV is the large file size (often it’s the reason why people convert WAV to MP3).
RA is popular with internet broadcasting as it can be played at the same time as it’s downloaded. Many RA files are protected which means that they can’t be converted to other formats.
CDA format is common for commercial compact discs. The CDA files can be played only from a CD-ROM. The widespread mistake is the attempt to copy tracks from CD to hard drive and then try to convert them. The right way to do is to rip CD and then convert the tracks to the format you need. Total Audio Converter allows that in one step process. You just hit RipCD button and set the target format in the wizard.
FLAC stands for Free Lossless Audio Codec. Due to the lossless compression scheme FLAC is good for classical music and other things where the quality of sound is crucial.
APE is the main competitor of FLAC and is similar to it in features. It is another lossless audio compression format.
AAC is good at compressing music if the purpose it to get the least size. Most people find AAC the best solution used to compress music to listen to it on mobile phones. Others say that AAC sounds awfully compared to MP3.
The true audio format (TTA) is another good lossless format. Imagine that you can compress 20 audio CDs to one DVD without any loss in quality! Unfortunately, not many audio players support TTA.
So the truth is that every format is good for some particular purpose. Choose yours (and be sure you can always convert between all of them with Total Audio Converter)!