Sector
A division of a storage medium
on a hard drive or diskette that is a wedge shaped section of one of the circular tracks. Each arc is a sector that typically holds 512 bytes of data and is given a sector number for interleaving purposes, so the term sector may refer to the entire single arc. The size of sectors can be customized to maximize the storage area. For example, if a user stores smaller files, decreasing the sector size allows more files to fill the space without any leftover room.
In the picture to the right, is a visual example of what the sector would look like on a disk
platter.
Also see: Bad sector, Boot sector, CHS, Hard disk drive definitions