Basically, magnetism is the force that causes a nail or paper clip to be pulled toward a magnet. Play around with a magnet and you'll quickly see magnetism in action!
But HOW does magnetism work?
That's a little harder to explain. But start with this...
Imagine two kids, trying to pull a wagon. One pulls from one side, and the other pulls from the exact opposite side.
What happens? The wagon doesn't move!
Now, imagine that the two kids realize that it isn't working and switch positions. The both pull from the same side.
Everything around you is made up of tiny particles. One of those particles is the electron.
These electrons are soooo tiny, that you can't see them without the most powerful of microscopes. As the name might suggest, electrons have an electrical charge. And whenever electricity moves, a magnetic field is created.
So, if these electrons are in everything, and they're magnetic, how come only some metals are magnetic, and not, for example, the family dog?
Think back to the example of the kids pulling the wagon. In most things, the electrons send their magnetic pull in different directions. If you're pulling on something from all different directions, it's not going to move.
In metals that are magnetic, the electrons are all facing the same way. So when they all pull in the same direction, things will move!