Magnetic tape data storage is a system for storing digital information on magnetic tape using a digital recording. Modern magnetic tape is most commonly packaged in cartridges and cassettes. The device that performs writing or reading of data is a tape drive. Autoloaders and tape libraries automate cartridge handling. For example, a common cassette-based format is Linear Tape-Open, which comes in a variety of densities and is manufactured by several companies.
Although the magnetic tape was initially primarily for data storage, newer uses included system backup, data archive, and data exchange.
Bytes Per Inch is the metric for the density at which data is stored on magnetic media. The term BPI can refer to bits per inch, but more often refers to Bytes per inch.
The term BPI can mean bytes per inch when the tracks of a particular format are byte organized as in 9-track tapes.