Hands-On Design Patterns with C# and .NET Core

An interface

In C#, an interface defines what an object contains, or its contract; in particular, the methods, properties, events, or indices of the object. However, the interface does not provide implementation. Interfaces cannot contain attributes. This is in contrast to a base class, where the base class provides both the contract and the implementation. A class that implements an interface must implement everything specified in the interface.

An abstract class An abstract class is a bit of a hybrid between the interface and base class as it provides both implementations and attributes as well as methods that must be defined in the child classes. Signature The term signature can also be used to describe the contract of an object.