What are fossil fuels?

About 97 per cent of the energy we use in our homes and factories is generated from coal, oil and natural gas, which are called fossil fuels. These were fall formed from organic (once-living) matter. Coal consist of the remains of land plants, while oil and gas were formed from the remains of tiny plant and animals which lived in lakes and seas. Oil and gas are more important fuels than coal. They are easier to extract and, by weight, they give out more heat.