WTF is "Ion Propulsion"

I recently went to a celebration of the satellite Voyager II, and drunkenly watched youtube videos of various satellites (boy, are they something!). One component of satellite travel I didn't understand was Ion Propulsion. I wasn't alone though, no one else seemed to understand either. Heck, the term itself sounds far far more complex than it actually is. When I first heard the term, I imagined small rings of steam emitted Jetson-style. However...

How does solar electric propulsion (ion propulsion) work?

Solar electric propulsion takes advantage of magnetism and electricity to push a ship through space. Electricity, generated by the ship's solar panels, gives a positive electrical charge to atoms inside the chamber. They are pulled by magnetism towards the back of the ship and then pushed by magnetic repulsion out of the ship. (This is like what happens when you hold the same pole of two different magnets close to each other. They repel each other.) This steady stream of atoms going out of the spacecraft gives it the thrust it needs to go forward through space.

Courtesy of Northwestern University