Bootstrap loader
Alternatively referred to as bootstrapping or boot loader, a bootstrap loader is a program that resides in the computers EPROM, ROM, or other non-volatile memory that automatically executed by the processor when the computer is turned on. The bootstrap loader reads the hard disk drives boot sector to continue the process of loading the computers operating system. The term boostrap comes from the old phrase "Pull yourself up by your bootstraps."
The boot loader has been replaced in computers that have an Extensible Firmware Interface (EFI). The boot loader is now part of the EFI BIOS.
Also see: Boot, BOOTP, EFI, MBR, Operating System definitions, VBR