This term is used for many forms of generating electricity (or just distributing it). Some of those primary or secondary energy sources are:

• Converting electricity, for example alternating current to direct current. Usually, it is used for well-regulated lower voltage electronic devices. Typically 120 or 240 volt AC (alternating current) is converted to a DC (direct current).
• Batteries – these are devices that store chemical energy and supply electrical form of it
• Energy storage systems – electrochemical, electrical, mechanical, potential (gravity) and thermal
• Solar power – it is a technology of obtaining usable energy from the sun to use it for heating, generate electricity with it or desalinate seawater.
• Electrical generators – these are devices which use electromagnetic induction to create electrical energy from mechanical energy source.

People have been using electricity for powering human technologies about 120 years. First power plants used wood to create energy, nowadays petroleum, natural gas, coal and nuclear power are being used. In some places hydrogen, solar energy, tidal harnesses, wind generators and geothermal sources are also being used but not to same exetnt as forementioned forms of supplying energy.

Electricity became inseparable in everyday life when transporting electricity over great distances and therefore supplying electricity to more people became possible.