Audacity is a free software, cross-platform digital audio editor and recording application. It is available for Windows, Mac OS X, Linux and BSD. Audacity can also be used for post-processing of all types of audio, including podcasts by adding effects such as normalization, trimming, and fading in and out. Audacity has also been used to record and mix entire albums, such as by tUnE-yArDs. It is also currently used in the OCR National Level 2 ICT course for the sound creation unit.

Audacity`s features include the following:

Importing and exporting of WAV, AIFF, MP3 (via the LAME encoder, downloaded separately), Ogg Vorbis, and all file formats supported by libsndfile library.
Versions 1.3.2 and later support Free Lossless Audio Codec (FLAC).[10] Version 1.3.6 and later also support additional formats such as WMA, AAC, AMR and AC3 via the optional FFmpeg library.
Recording and playing back sounds
Editing via Cut, Copy and Paste (with unlimited levels of Undo)
Multitrack mixing
A large array of digital effects and plug-ins. Additional effects can be written with Nyquist
Built-in LADSPA plug-in support. VST support available through an optional VST Enabler.
Amplitude envelope editing
Noise Removal based on sampling the noise to be removed. Surface noise from records, for example, can be removed with hardly any discernable effect on the music.
Audio spectrum analysis using the Fourier transformation algorithm
Support for multi-channel modes with sampling rates up to 96 kHz with 32 bits per sample
Precise adjustments to the audio`s speed while maintaining pitch (Audacity calls it changing tempo), in order to synchronize it with video or run for a predetermined length of time
Changes to the audio`s pitch without changing the speed
Features of modern multi-track audio software including navigation controls, zoom and single track edit, project pane and XY project navigation, non-destructive