The word electricity is derived from the Greek word ‘electron’ which means amber. In the sixth century BC, a Greek philosopher Thales found that when a piece of amber (a kind of resin) is rubbed with fur, it acquires a remarkable property; it attracts small pieces of leaves, cork or dust. Today, we know that many other materials, such as hard rubber, nylon, plastic, glass, sealing wax etc. shows the same effect. A substance which exhibits this effect is said to be electrified or charged.
It is possible to impart an electric charge to any solid material by rubbing it with another material and amber is just one of the substances which shows the effect much strongly. It should be noted that both the rubbing and rubbed materials are electrified simultaneously. They are said to have acquired electric charges. Electrification of bodies through friction is called frictional electricity. It is also called static electricity as the charges so developed cannot flow from one point to another.
You can see this kind of effect by doing a simple experiment. Place a few tiny pieces of paper on a table. Take a plastic ruler or comb and rub it with dry hair or a piece of wool and bring it near the pieces of paper. You will observe that the pieces of paper are attracted towards the rubbed ruler or comb.
You can also see this effect when you put off your sweater in winters. Put off the sweater in a dark room and sometimes, you will observes the sparks while doing this. This is due to the same reason i.e. frictional electricity.