Fuels are an important source of energy. With them life is difficult as fuels are used in many day to day works like producing energy which is used in many purposes like running vehicles. It also helps to keep oneself warm in the form of coal which is used in heaters etc. It is important to conserve fuel as fuels or fossil fuels are the remains of plants and animals buried deep under the earth millions of years ago. They are present in limited quantity and if once get exhausted, then will take millions of years in their formation. Also continuous burning of fossil fuels releases many harmful gases which results in global warming. Thus it should be not excessively used i.e. it should be used in limit.