BIOS

BIOS, which is an abbreviation of basic input/output system, handles the most basic interaction between the physical components (hardware) and the software (operating system) of a computer.

BIOS controls thing such as the system time and date, the booting order (i.e. where the computer starts to look for the operating system and in which order) and certain hardware features (for example, whether legacy USB support is enabled or not), among other things.

How to enter BIOS
The key which you need to press to access the BIOS is shown briefly when you boot the computer, during the moment when the computer manufacturer's logo is also shown. For most computers, this key is usually either F2, F12 or Esc, but it might also be a different key or a key combination. For example, to enter BIOS on a Fujitsu-Siemens P1610, you need to either click the mouse (in other words, touch the screen) or press the Enter key.

BIOS passwords
It is possible to restrict access to BIOS. Usually this is done by setting a password, which is referred to as a BIOS password. While setting a BIOS password might be useful for some users, in most cases it's more troublesome than anything else. If the BIOS password is forgotten, in the worst case the laptop can end up being nothing more but an expensive paperweight.

IBM's/Lenovo's ThinkPad laptops can have two different passwords, a user password which allows to view settings and modify some, and a supervisor password, which allows to modify all settings, including (but not limited to) boot order, system time and date and more.

Different laptops store BIOS passwords in a different way, but what's common to almost all laptops is that removing the CMOS battery will not clear BIOS password(s), like it does with desktop computers. IBM's/Lenovo's ThinkPad's BIOS passwords are among the most difficult ones to bypass/clear.

For certain laptop lines, such as the Panasonic Toughbook line, instructions on how to bypass the BIOS password can be found on the official service manuals.

Laptop manufacturers will often claim that to remove the BIOS password, the motherboard needs to be replaced, which is an expensive procedure.

Many Internet forums prohibit the discussion of BIOS password bypassing.