Pistols are the most basic type of Firearms availible. They tend to do 1 high-numbered die in damage (1d20 to 1d25 is not uncommon). Because of this, they have variable damage and are usually a poor weapon choice. As with all guns, it's only useful if you have a high firearms skill, otherwise most of your time will be spent missing.
Pistols can use both bullets and energy cells as ammo. See Ranged Weapons for distance modifiers.