Hybrid vehicles are vehicles that use a combination of two or more power sources to propel them. Typically, hybrid vehicles combine a traditional internal combustion engine with an electric motor and battery. This allows for improved fuel efficiency, reduced emissions, and in some cases, increased performance. Hybrid vehicles can be classified into different types, such as full hybrids, mild hybrids, and plug-in hybrids, depending on the level of integration between the combustion engine and the electric motor. Research in hybrid vehicles focuses on improving the technology, increasing adoption rates, and exploring new ways to reduce fuel consumption and emissions in the transportation sector.