Audacity is a free multi-track audio recorder, editor and mixer. Audacity is a cross-platform software available for Mac, Windows and Linux.
Audacity Key Features:
Audacity can record live audio through a microphone or mixer, or digitize recordings from other media. With some sound cards, and on any recent version of Windows, Audacity can also capture streaming audio.
Import sound files, edit them, and combine them with other files or new recordings. Export your recordings in many different file formats, including multiple files at once.
And much more.