Typical case screws are used to screw on the case covers and anchor plug-in cards to the case.

A drive screw's thread is finer and thinner than screws used for the case. The head is smaller, too. This kind of screw is generally used to affix the drives in the drive bays, and to screw the motherboard to the case.

Spacers are screwed into the backplate for the motherboard.

What Are Jumpers?

Jumpers are short and sweet.

A jumper is nothing more than a metal bridge that connects two contacts. We don't see the metal, though, because it's covered with plastic. Jumpers are often used to configure the PC. For instance, you can use them to set the processor speed or change a drive from a "master" to a "slave." Pictured above is a classic jumper, as used on drives and boards just about everywhere.