While the RAM is used as working memory, the computer also needs a place to
store data for the longer term. Most of today’s personal computers use a hard disk
for long-term data storage. A hard disk is where data is stored when the computer
is turned off and where it is retrieved from when the computer is turned on. Why is
it called a hard disk? A hard disk consists of a stack of disks inside a hard metal
case. A floppy disk (discussed below) was a removable disk that, in some cases at
least, was flexible, or “floppy.”