Adapter design patterns come under the structural design pattern, according to this design pattern two incompatible classes work together that couldn't otherwise because of incompatible interfaces. This pattern works as a bridge between two incompatible interfaces. This pattern is used when two inferences of the application are incompatible in their functionalities, but these functionalities need to be integrated as a business requirement.

There are many real-life examples where we can use the adapter pattern. Suppose you have different types of electric plugs such as cylindrical and rectangular plugs, as shown in the following figure. You can use an adapter in between to fit a rectangular plug in a cylindrical socket assuming voltage requirements are met: