A letter or name assigned to a disk or tape drive. In a PC, the basic drive mappings are A: for the floppy disk (B: used to be the second floppy) and C: for the primary hard disk. When new peripherals are added to the system, additional drive mappings are assigned by the operating system based on the next available letter (D:, E:, etc.).

Network Drives
In a network, drive mappings reference remote drives, and you have the option of assigning the letter of your choice. For example, on your local machine, you might map S: to refer to drive C: on a server. Each time S: is referenced on the local machine, the drive on the server is substituted behind the scenes. The mapping may also be set up to refer only to a specific folder on the remote machine, not the entire drive.

Universal Naming Convention
In the days of Windows 3.1, drive mapping was the only way to reference a remote drive. Starting with Windows 95, both drive mapping and the universal naming convention (UNC) can be used. With UNC, a computer name and drive name replace the letter-colon designation. See dynamic drive mapping, redirector and UNC.