Physics-electrons and sockets?

The moment you plug in your device, you "complete the circuit". A potential electrical difference is introduced to the system and things start to happen.

Typically, the convention is to say positive flows to negative. Although in reality the opposite is true, since electrons are negatively charged, they actually head towards the positive potential well.

All that aside, what's really happening is the electrons are moving in a giant conga-line through the circuit. At points where things like your hair-dryer are present, its a little harder for them to get through. They have to push because there is resistance and from this resistance energy is given to the mechanisms inside your hair dryer.

By the way the conga-line analogy is used to emphasize the true nature of electron movement in wires. They don't zip along at near light speed, but rather bump each other gradually forward, but the rate of bumps is fast!