Gasoline is a liquid fuel obtained from crude oil through fractional distillation. It is a dark liquid used as fuel in internal combustion engines. During fractional distillation, hydrocarbons with lower boiling points are separated at the top of the distillation tower. Different hydrocarbon fractions obtained from crude oil are used as various fuels based on their boiling points and number of carbon atoms. Properties like boiling point, density, viscosity and heating value of fuels increase with increasing molecular size and carbon content.