Magnetic tape is a recording medium for data storage on a long narrow strip of magnetisable material.

Magnetic tape generally consists of a thin magnetisable coating on a long narrow strip of plastic. A device that stores data on magnetic tape is called a tape drive or tape streamer.

Magnetic tape allows very large quantities of data to be stored for a long period of time. For long-term data storage, magnetic tape can suffer from deterioration called sticky-shed syndrome, which is caused by absorption of moisture into the binder of the tape and can render it unreadable.

A tape drive uses precisely-controlled motors to wind the tape from one reel to another, passing a read/write head as it does. Magnetic tape has been used for over 50 years and many advances in tape formulation, packaging, and data density have been made. Modern magnetic tape is usually packaged in cartridges or cassettes. Autoloaders and tape libraries are often used to automate cartridge handling.

In many situations, tape remains a viable alternative to hard disks due to its lower cost per bit. Though the data density of tape is lower than for hard drives, the available surface area on a tape is much greater. The highest capacity tape media hold approximately the same amount of data as the largest available hard drives (about 1 TB in 2007). Tape offers enough advantage in cost to make it a viable product, particularly for backup, where the recording media must be removable.