The piece of Hardware that stores your programs and data "permanently" - ie after the power goes off. You probably know what a hard disk is.

Hard drives used to have capacity measured in MegaBytes -- these days it's in GigaBytes.

A typical cheap IDE hard disk drive these days might cost around NZ$200 for 40-60 GibiBytes of data. SCSI drives are typically slightly more expensive.

The standard method of measuring large amounts of data (in the mainstream media) appears to be LibraryOfCongress x n.

This ( http://www.wlug.org.nz/archive/images/platter-lowres.jpg ) is a disk platter used at StanfordUniversity in the 1960s. I put a $1 note in the lower-right corner to give you an idea of the platter's size. This platter could store 4 megabytes of data. The black mark around it is from a disk head crash (!!).

See also DrivePartitioning?, BackupNotes, FileSystems and HowToUltraDMA?.