Hard Disk Drive

A non-volatile magnetic storage device that stores digitally-encoded data with a much larger capacity and higher data-transfer rate than a diskette. It is  typically located inside the computer’s system unit, although external hard disk drives are common. A typical personal computer hard disk drive might store between 120 gigabytes and 1 terabyte of data, where a 3.5 inch diskette stores approximately 1.4 megabytes.