A DC-DC converter is an electronic device that converts direct current (DC) from one voltage level to another. It is widely used in applications where devices require different voltage levels than those provided by the power source. There are several types of DC-DC converters, including buck converters (which step down voltage), boost converters (which step up voltage), and buck-boost converters (which can both step up and step down voltage). These converters are essential in various fields such as automotive, telecommunications, and portable electronics to ensure efficient power management and supply.