How does the hybrid engine work?

Hybrid engines use two or more power sources. They consist of a usual fuel engine, complemented by a pollution-free engine, an electric engine for example. The fuel engine and brakes are used to recharge the batteries for the electric engine, eliminating the need to plug in while unused. When brakes are applied, some of the energy being used to stop the vehicle is collected by the regenerative brakes of the electrical engine. Hence, the electrical engine takes control when cruising, stopping or slowly accelerating, reducing the use of fuel.