The single-pole switch is the general-purpose workhorse of switches. It is used to control a light, receptacle, or other device from a single location. A characteristic feature of a single-pole toggle switch is that it has ON and OFF markings on the toggle. This is something you will not find on three-way or four-way switches.
A single-pole switch has two brass-colored screw terminals and is wired to the "hot" (current-carrying) wire, which is usually black. One brass terminal is for the incoming hot wire and the other is for the outgoing hot wire to the device. Most single-pole switches also include a ground terminal for connecting the circuit's ground wire.
As a general rule, neutral (usually white) wires are not connected to switches. However, sometimes you may see a white wire attached to the switch, and this is when it is functioning as a hot wire. In this case, the white wire should have a wrap of black tape on it near the switch terminal to indicate that the wire is a hot wire and not a neutral wire.