Availability

Audacity is an opensource project listed at sourceforge. It is available for download for free at sourceforge.net

Project Audacity

Audacity

Digital Audio Editor

Audacity is a program that manipulates digital audio waveforms. In addition to recording sounds directly from within the program, it imports many sound file formats, including WAV, AIFF, AU, IRCAM, MP3, and Ogg Vorbis.
It supports all common editing operations such as Cut, Copy, and Paste, plus it will mix tracks and apply plug-in effects to any part of a sound. It also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications. It is not MIDI editor.
Audacity works with tracks, that contain one audio file. This file is editable and all actions are undoable. Undo's are instantaneous. Almost anything is undoable, including importing and deleting tracks!