Byte
The common unit of computer storage. A byte holds the equivalent of a single character, such as the letter A, a dollar sign or decimal point.

CD (Compact Disc)
A digital audio disc that contains up to 72 minutes of hi-fi stereo sound. Other forms of CDs, such as CD-ROMs and CD-I discs, all stem from the audio CD.

Data Compression
A technique that allows more data to be stored on a given tape - usually at lower quality. Most manufacturers assume a 2 to 1 data compression can be achieved (i.e. 2 MB of data on 1 MB of tape), but actual results depend on the data being stored.

Disc
An alternate spelling for disk. Compact discs and videodiscs are spelled with the "c." Most computer disks are spelled with a "k."

Disk Cartridge
A removable disk module that contains a single hard disk platter or a floppy disk.

DVD
The disc is the same diameter as a CD-ROM, but can be recorded on both sides. Each side holds 4.7GB. DVD-ROMs are read-only DVDs, DVD-Rs are write once, and DVD-RAMs are rewritable.

Gigabyte (GB)
A measure of data storage, equivalent to 1,000 megabytes (MB), or approximately 1 billion bytes of data.

Hard Disk
The primary computer storage medium. Hard disks provide fast retrieval because they rotate constantly at high speed, from 3,000 to 10,000 rpm.

Helical Recording
A way to write information to a tape that involves spinning the writing head in the reverse direction to the tape movement. Helical scan drives can hold more information on a given tape length than a standard recording head. VCRs are a common example of helical recording.

IDE (Integrated Drive Electronics)
A type of hardware interface widely used to connect hard disks, CD-ROMs and tape drives to a PC.

Incremental Backup
A backup method which only saves the files within a system that have changed since the last backup. Incremental backups require much less storage space, but take longer to restore after a crash or disaster. Many businesses conduct full backups each week, while conducting the quicker incremental backups each day.

Jaz Disk
A high-capacity removable hard disk system from Iomega Corporation. Jaz drives come in SCSI and IDE models and read 1GB and 2 GB cartridges.

Jukebox
Large networks often need more storage capacity than is available in a single tape. A jukebox automatically loads and unloads tapes from the player during a backup.

Megabyte (MB)
One million bytes. Also MB, Mbyte and M-byte.

Native Capacity
The storage capacity of a drive when no compression techniques are used. Comparing drives based on their native capacity eliminates differences in manufacturer assumptions concerning file compression.

SCSI (Small Computer System Interface)
Pronounced "scuzzy". SCSI is a hardware interface that allows for the connection of up to seven or 15 peripheral devices to a single expansion board that plugs into the computer called a SCSI host adapter or SCSI controller.

Storage Device
A hardware unit that holds data.

Storage Media
Refers to disks, tapes and optical discs (CD and DVD).

Tape Backup
The use of magnetic tape for storing duplicate copies of hard disk files.