What does it mean to defragment a hard disk?
Answer: Over time, new files get written to your hard disk and old ones get deleted. When files are removed, gaps are created in the hard drive where new data can be written. Sometimes the new data doesn't quite fit in the gaps and some files get written in multiple areas on the hard disk. These files become "fragmented," meaning they consist of fragments of data. Because the hard drive has to scan multiple parts of the the disk to read a fragmented file, it can slow down the operation of the computer.
Defragmenting the hard disk cures this problem. A hard disk utility, such as Norton Utilities, can put file fragments together to create contiguous files. Contiguous files are read more efficiently by the hard drive and therefore lead to faster data access. Some defragmentation programs can also optimize the hard disk, which places similar files in similar locations. For example, program files are stored in one area, system files in another, and documents in another area of the disk. It is a good idea to defragment you hard drive about once a month during typical use.