What is the purpose of an electrical capacitor and how is it wired?

Capacitors come in all shapes and sizes, but they usually have the same basic components. There are the two conductors (known as plates, largely for historic reasons) and there's the insulator in between them (called the dielectric). The two plates inside a capacitor are wired to two electrical connections on the outside called terminals, which are like thin metal legs you can hook into an electric circuit.
You can charge a capacitor simply by wiring it up into an electric circuit. When you turn on the power, an electric charge gradually builds up on the plates. One plate gains a positive charge and the other plate gains an equal and opposite (negative) charge. If you disconnect the power, the capacitor keeps hold of its charge (though it may slowly leak away over time). But if you connect the capacitor to a second circuit containing something like an electric motor or a flash bulb, charge will flow from the capacitor through the motor or lamp until there's none remaining on the plates.

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