Electricity is nothing but flow of electrons from one body to another. In order to understand this is some detail, we need to understand the structure of an atom. An atom consists of three elements - electrons, protons and neutrons. Electrons are negatively charged (-) particles, protons are positively charged particles (+) and neutrons are neutrally charged or they have no charge.

Now let us say there are two objects - A and B with 10 electrons and 10 protons each. Due to friction or any other reason, 2 electrons from the outer orbit of Object A flows away to Object B. Now there are 8 electrons in Object A and 12 electrons in Object B. The net result of this flow of electrons is that Object A will get negatively charged because of excess electrons and Object B will get positively charged because of Deficit of electrons. This is how electricity is produced.

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There are mainly 2 kinds of Electricity: Static Electricity and Current Electricity.

Static electricity is an electrical charge that is at rest. This is created by an imbalance of electrons that stay on a specific surface, or in the environmental air. The imbalance of electrons (in all cases, is caused by absence or surplus of electrons) thus causes an electrical field that is capable of influencing other objects at a distance. You can generate static electricity by simply combing your hair with a nylon comb. The electrical charge transferred to the comb will cause it to attract the hair, or, if you like, to pick up little scraps of paper. Lightening is another example of static electricity.

Current electricity can be defined as electricity that flows through a circuit, or a continuous unbroken path. This path is most often a good conductor or electricity such as copper.

In Physics, the Law of Conservation of Energy says that energy can neither be created nor be destroyed. Energy can only be transformed from one type to another. This means that in order to generate electricity, we have to use another kind of energy as fuel. Let us understand this clearly by going through the history of electricity.

Also Read: History of Electronics

Benjamin Franklin (1706-1790): His kite experiment demonstrated that lightning is electricity. He was also the first to use the terms positive and negative charge.

Thomas Seebeck (1770-1831): Discoverer of the "Seebeck effect". He twisted two wires made of different metals and heated a junction where the two wires met. He produced a small current. The current is the result of a flow of heat from the hot to the cold junction. This is called thermoelectricity.

Michael Faraday (1791-1867): Electromagnetic induction. He also explained how electric currents works.

James Maxwell (1831-1879): Translated Faraday's theories into mathematical expressions.

Thomas Alva Edison (1847-1931): Invented theElectric Bulb

Nikola Tesla: Devised the polyphase alternating-current systems that form the modern electrical power industry.

Otto Hahn (1879-1968): He explained the process of nuclear fission by which nuclei of atoms of heavy elements can break into smaller nuclei, in the process releasing large quantities of energy.

Albert Einstein (1879-1955): He explained thatthat one gram of mass can be converted into a torrential amount of energy.

Generating electricity need knowledge about electronics, engineering, physics and chemistry. There are various sources to generate energy. – Both renewable and non-renewable. Let us now understand how to generate electricity in detail.

Hydroelectricity or hydro electric power is one of the most widely method of generating electricity. Water is stored is a high dam or an artificial or natural lake or reservoir. This water stored in a high place has is gravitational potential energy. Down this source of falling water is a power station equipped with water turbines. Potential energy is converted to kinetic energy when water falls down. This kinetic energy rotates the water turbines to generate electricity. Have a look at the video on the right.

Wind is a renewable source of generating energy. Kinetic energy of moving air rotates fan blades of windmills. These blades are connected with turbines. Rotating blades of windmills rotate the turbine to generate electricity. Have a look at the video on the right.

Solar energy or energy stored in the rays of the sun is another renewable source to generate electricity. Artificially created solar cells are used to store and convert solar energy into electricity. These solar cells are mainly of two types: Crystalline silicon solar cells and "Thin-film" or polycrystalline PV cells. To understand how solar panels work to generate electricity- Read: How Solar Panels Work to Generate Electricity

Fossil Fuels: Fossil fuels such ascoal and oil is used to generate heat. This heat converts water into steam at very high temperature and high pressure. This steam at high pressure drives a steam turbine. The rotating shaft of the steam turbine is coupled to the armature of the alternator to generate electricity.

Tidal Power and Wave Power: This is comparatively a new technology to extract energy from movement of water in a tidal estuary and from motion of waves. The basic principle behind generating electricity in all means is the same - to drive a mechanical turbine.

Geothermal Energy: This energy from within the earth.The earth from inside is too hot. Volcanoes are evidence of this. This heat from within the earth can be used to turn turbines and produce electricity. This technology is still a subject matter of further research and engineering.

Nuclear Energy: Nuclear fission is a process in which radioactive atomic nuclei break down and release energy in the form of radiation. This energy is further used to turn turbines and produce electricity.