Electricity is the flow of electrons between atoms. Objects become charged when they gain or lose electrons - gaining electrons makes them negatively charged, while losing electrons makes them positively charged. There are two main types of electricity: static electricity occurs when electrons build up on an object, while current electricity refers to the continuous flow of electrons from one place to another. Materials that conduct electricity well are called conductors, while insulators do not conduct electricity easily. Static electricity can be generated through friction or contact between objects and causes electrons to transfer.