Static electricity is a problem that affects not only computers, but almost all consumer electronics. If you plan on installing new hardware in your computer and you have not done it before, there are some things you should know to protect your computer.
All computer hardware is shipped in static bags, those thick silvery sleeves, to prevent static from damaging them in shipping. Most computer hardware is made up of integrated circuits, those little black pieces with metal wires coming out of them. They are called integrated circuits because inside of them are thousands, millions, or billions, of smaller components, such as transistors, capacitors, and resistors. They are intended to run as voltages that range from around 1V, to around 12V.
Many people have experienced the sensation that when they walk across a carpet and maybe drag their feet, then they touch a door knob, they feel a small static jolt. While it feels small to people, that static discharge is actually the result of a voltage difference between their hand and the door knob of possibly hundreds of volts.
Such a high voltage can actually present a problem if you were to touch a computer chip instead of the door knob. As mentioned before, these chips are intended to operate at voltages that are generally less than 10V, so applying over 100V to them can damage the components within the chip.
One thought to ease the minds of people out there is that chip manufacturers go through great lengths to test their chips to ensure that they operate as they want them too, which includes putting them through ESD testing, or ElectroStatic Discharge testing. This means that they put their chips in a test device that will shock it with thousands of volts, and then make sure that the chip still works. They generally only perform ESD testing on a small sample of the chips they produce to ensure that statistically the chips can handle a short burst of static discharge, so it better to be safe than sorry when handling computer components to avoid accidentally getting a static discharge inside your computer.
One way to try and prevent accidentally shocking the inside of your computer is to touch either a piece of metal in your computer or the metal frame of a desk or door, which basically grounds you and prevents you from creating a static discharge inside of your computer.