Audacity is a free, easy-to-use and multilingual audio editor and recorder for Windows, Mac OS X, GNU/Linux and other operating systems.
http://audacity.sourceforge.net/
FLOSS Manuals is a collection of manuals about free and open source software together with the tools used to create them and the community that uses those tools.
http://www.flossmanuals.net/audacity/
http://ardour.org/
record
mix
edit
collaborate
