Answer:
There are three main categories of energy sources: fossil fuel, alternative, and renewable. Renewable is sometimes, but not always, included under alternative. Fossil fuels formed over millions of years ago as dead plants and animals were subjected to extreme heat and pressure in the earth's crust. Energy consumption is highest at the moment in developed countries and countries with high populations. This is due to a high concentration of industry, high levels of car ownership and high domestic usage from homes filled with appliances. The sun is the main source of energy on Earth. Other energy sources include coal, geothermal energy, wind energy, biomass, petrol, nuclear energy, and many more. Energy is classified into various types based on sustainability as renewable sources of energy and non-renewable sources of energy.