There's electricity inside matterHas your hair ever stood on end after you slid down a slide? This is because you and your hair have collected an electrostatic charge from the friction. "Electrostatic" means that the electric charge has stuck on you and is not moving. Apart from your hair moving, you cannot feel static electricity.
There are two kinds of electric charge- positive and negative. Your hair standing on end shows that when electric charges are the same (both positive, or both negative) then they repel each other. On the other hand, if charges are opposite (one positive and one negative) then they attract each other.You should learn this simple rule- like charges attract and unlike charges repel.When a positive charge meets a negative charge, they cancel each other out. That is like a positive number joining a negative number, making zero. We call a zero electric charge, neutral. That is, a positive and negative charges neutralize each other. Neutral objects don't attract or repel each other.
After you shoot down a plastic slide at McDonalds, do you sometimes notice that a spark jumps across when someone touches you? This is because you have picked up an electric charge, and that's because there's lots of electricity inside matter. This video explains how electric charges work, and how important they are for atoms.