Audacity is a free, open source digital audio editor software that allows users to record, edit, and export audio files. It has many of the basic features of a tape recorder, including recording audio, playing audio, and editing features like removing background noise, mixing tracks, adding effects, and adjusting speed. The document provides step-by-step instructions on how to download, install, and use Audacity to record audio, save files in MP3 format, and send recordings via email. It also lists several ways Audacity can be used for teaching purposes, such as conducting discussions, having students record assignments, and compiling audio lessons.