Linear Tape-Open (LTO), also known as the LTO Ultrium format, is a magnetic tape data storage technology used for backup, data archiving, and data transfer. It was originally developed in the late 1990s as an open standards alternative to the proprietary magnetic tape formats available at the time. Upon introduction, LTO rapidly defined the super tape market segment and has consistently been the best-selling super tape format. The latest generation as of 2025, LTO-10, can hold 30 TB in one cartridge, or 75 TB with industry-standard 2.5:1 compression.