This section reviews some terms used to describe basic electrical principles. If you are just beginning to learn about electricity, you should check a secondary-school text for a good introduction to the subject. Books on how to wire houses are a good introduction to the subject of 110/230V AC electricity.
Electricity is power provided by the flow of very small charged particles called electrons through metal wires. Because electrons are so small, it takes millions of them moving together in the same direction to develop a detectable electric current. Wires carrying electricity do not appear any different from wires not carrying electricity (although they may get a bit hot), so electricity is invisible to the human eye when travelling through wires.
Not all substances can carry electricity. Those that can carry electricity are called conductors and those that cannot are called insulators. Metals such as copper and aluminium are good conductors of electricity, as are salty liquid solutions called electrolytes. Wood, plastic and rubber cannot carry electricity and thus are called insulators. Note that wire cables are wrapped with plastic insulation to prevent the electricity from deviating from its pathway.