BIOS password

A BIOS password is authentication information that is sometimes required to log into a computer's basic input/output system (BIOS) before the machine will boot up. 

BIOS is the program a computer's microprocessor uses to control the computer's initial boot sequence and hardware initialization. The BIOS password is stored in complementary metal-oxide semiconductor (CMOS) memory. In some computers, a small battery attached to the motherboard maintains the memory when the computer is off. 

Because it provides an extra layer of security, a BIOS password can help prevent unauthorized use of a computer. A BIOS password can also be a liability, however, because if the computer owner forgets his password or a corporate user hands in his machine without disclosing the BIOS password, the computer will not boot up.  

A BIOS password can be reset by contacting the vendor for directions. Resets typically involve the use of backdoor BIOS passwords. These are passwords created by the BIOS manufacturer that will work no matter what password the user has set up.  User-created passwords can sometimes be cleared by removing the CMOS battery or by using special BIOS password cracking software.