These are called conductors. Most metals are good conductors. One very common way is to rub two objects together. The more rubbing, the more electrons move, and the larger the charges built up. It is simply the contact between two different materials.
Static electricity is the imbalance of positive and negative charges.
Now, positive and negative charges behave in interesting ways. Well, it's true. A charged object will also attract something that is neutral. Think about how you can make a balloon stick to the wall. If you charge a balloon by rubbing it on your hair, it picks up extra electrons and has a negative charge.