Computers, Computer Science 1. The hardware and associated software needed for communication between processors and peripheral devices, to compensate for the difference in their operating characteristics (e.g. speeds, voltage and power levels, codes, etc.). 2. Abstract methods —and, optionally constants— but you can think of it as a contract between the class that implements it and the class's users. By implementing the interface, you agree to provide definitions for each method declared in the interface. Implementing an interface is similar to subclassing an abstract class.