Solid State Relay
Solid state relays (commonly abbreviated to SSR) are great devices to switch on and off large AC loads. For example, you can use a SSR to switch on a blender, or house lights. Plus, they are very easy to use. See the picture below for a fully functioning SSR circuit.
You can see the AC plug and socket to go in between the power outlet and the device to be switched. the two thin white wires are what controls the SSR. In the particular SSR shown pictured (bought for $7 shipped from eBay), an input signal of 3-32v dc will turn on the SSR.
Connecting the SSR
The AC power cord has two lines, hot and neutral. Split the hot line and put it in line with the SSR as shown. The SSR has screw terminals, so all you have to do is strip the power cord wires, wrap them in a circle and screw them down.
The two small white wires are the input wires, one is ground, the other is the signal. Give a digital voltage (3v to 32v in this case) to trigger the relay.