Audacity

Audacity is a free, open-source software for recording and editing sounds. Available for Windows, Mac, and GNU/Linux. Download Audacity here. Make sure to download the additional Lame MP3 encoder if you want to export your audio as an mp3 file.

Pros:

• Record live audio.
• Supports basic audio editing; splicing, mixing, changing pitch or speed.
• User-friendly.

Cons:

• Works only with Ogg Vorbis, MP3, WAV or AIFF sound files.