Audacity

Audacity is a very useful digital audio editor and recorder that can be used on your Windows, Linux, BSD, and Mac OS X platform. Audacity was developed by Dominic Mozzoni who is now an employee of the internet giant Google but still the primary developer and maintainer of Audacity A few features of audacity are things like importing WAV, AIFF, MP3, and OGG. Audoacity also supports FLAC, multi-track mixing, plugins, noise removal, amplitude envelope editing, and more. Audacity supports a wide variety of languages and even includes tutorials on their website for other languages in addition to English.

 Audacity provides a simple interface that enables the user to edit basic sound tracks quickly and at the same time Audacity provides an interface that yields hundreds of effects and possibilities for generating new sound tracks. Also I've found Audacity very compatible with whatever files i'm working with and great to use on quick sound edits because you can easily import in, edit, and export or save your files.

 The most recent Audacity release is available for download here. You can access some Audacity plugins here which will extend the functionality of audacity so you can do even more. Also the website Free-Loops.com has alot of audio loops you can get started with in Audacity.