Any substance that is the contain the property of burn is known as fuel.

Fuel is a substance that is used to produce energy. It is a material that can undergo combustion or other chemical reactions to release energy in the form of heat or light. There are different types of fuels such as fossil fuels, biofuels, and nuclear fuels.

Fossil Fuels:

Fossil fuels are formed from the remains of dead plants and animals that have been buried deep in the earth's crust for millions of years. They are non-renewable sources of energy that are extracted from the ground. The three main types of fossil fuels are:

1. Coal: Coal is a black or brownish-black sedimentary rock that is formed from the remains of plants that lived millions of years ago. It is mainly used to generate electricity.

2. Oil: Oil is a liquid fossil fuel that is formed from the remains of marine organisms that lived millions of years ago. It is mainly used for transportation and heating.

3. Natural Gas: Natural gas is a fossil fuel that is formed from the remains of plants and animals that lived millions of years ago. It is mainly used for heating and cooking.

Advantages of Fossil Fuels:

- They are readily available and easy to transport.
- They are relatively cheap compared to other sources of energy.
- They are reliable sources of energy that can be used to produce electricity on a large scale.

Disadvantages of Fossil Fuels:

- They are non-renewable sources of energy that will eventually run out.
- They are major contributors to air pollution and climate change.
- The extraction and transportation of fossil fuels can cause environmental damage.

In conclusion, fuel is a substance that is used to produce energy. Fossil fuels are one type of fuel that is formed from the remains of dead plants and animals that have been buried deep in the earth's crust for millions of years. While they have advantages, they are also associated with significant environmental drawbacks.