Pro Tools
Pro Tools is a software package for professional sound and music editing, first created under the name Sound Tools by Digidesign, now a division of Avid. It is widely used in the post production, music, and radio industries, and serves as the de facto standard in some segments of those industries.It was one of the first programs that provided CD-quality (16-bit and 44.1 khz), multitrack editing on a personal computer, making it a widely used program in the sound recording industry. It became popular in the early 1990s primarily because it offered an interface that was user-friendly to the common producer who was still used to analog hardware. The software interface of Pro Tools emulates that hardware used in the professional studio coupled with plugins and effects, MIDI capablities (although currently the capabilities are low compared to similar software sequencers), and advanced audio editing capabilities.
Because a Pro Tools "system" is generally only available and functional in connection with the brand's relatively expensive hardware (called a TDM or HD system), many users chose to use other sequencing and recording software that allows them to use any soundcard they wish.
In response to this, Digidesign has since released a series of less expensive hardware products such as the 001 (discontinued), 002, 002/R, and MBox which run a limited "LE" edition of the Pro Tools software.
Recently Digidesign has released a free verion of Pro Tools that is not dependant on proprietary hardware. Pro Tools Free is limited to only eight tracks of audio (as opposed to 192 tracks in HD systems) and intended mainly for recording on location where hardware would be cumbersome, as well as being a convenient promotional tool for more capable (and costly) systems.