In computers, tape is an electromagnetic storage medium that typically is both readable and writable. A tape drive is the device that positions, writes from, and reads to the tape. A tape cartridge is a protectively-encased tape that is portable.

In early business computers, tape was a primary storage medium and computer system operators spent a lot of time mounting and unmounting tapes for different jobs at different times of the day. With the development of the magnetic disk, tape became a medium for backing up the large amounts of data on mainframes. Apart from any other consideration, one drawback of tape is that it can only be accessed by starting at the beginning and rolling through the tape until the desired data is located. For this reason, its main application use has been for batch processing of large amounts of data (payroll is the classic example).

Today, tape is still sometimes used on mainframes for archiving purposes. New forms of tape are being used for automatic backup. On personal computers, tape is also used for backup although Iomega's Zip drive and disk is much more popular.

For larger system backup, the Digital Linear Tape Drive (DLT) provides a very fast (800 Kbytes per second) backup to tape cartridges that hold either 20 gigabytes or 40 gigabytes of data and can be mounted in an automated library that holds enough cartridges to backup 5.2 terabytes of data. (The 264-cartridge system costs about $100,000.) Specifications are available at Digital's Web site. Other companies such as IBM also sell tape drives for backup and other purposes.