Not only is Audacity a cross platform, simple to use, and free. Audacity has become the standard application for editiing audio files.
How do I use it?
I use it to edit my tracks to make my custom ringtones. I use it to edit my audio files. I use it to remix my mixes. I use for simple audio effects. I use it for many things I and I can go on and on.
So check it out. Leave me a comment on how much you like or hate.