Everything in the world consists of tiny particles called "atoms." Atoms contain even tinier particles called "protons," "neutrons" and "electrons."
When you come in from playing in the snow and remove your hat, the hat rubs your hair and electrons move from your hair to the hat, creating a static charge. When objects have the same charge, they repel each other, which means they try to get as far from each other as possible.
When people think of static electricity, they often think of the shock it can cause. If you have ever scooted your sock-covered feet across the carpet, you have probably experienced the zap of static electricity.
As you walk over carpet in socks, your feet rub electrons off the carpet, leaving you with a slightly negative static charge. When you reach for a doorknob, you get a shock as electrons jump from you to the knob, which conducts electricity.
You've probably noticed that static electricity is more noticeable during the winter months. This is because the air is very dry.
In the summer, the humidity and moisture in the air help electrons move more quickly, which makes it harder to build up a big static charge.