Although interfaces in C# can have only properties, abstract classes in C# may have properties and fields. Typically, we use abstract classes to create an abstract base class that other classes ...

Until C# 8.0, an interface in C# could not contain method definitions. You could only include method declarations in an interface, and the members of an interface were public and abstract by default.

In derived classes, abstract methods are implemented with the same access modifier, type of argument, number and return type as the base class. Abstract methods can also be used to specify interfaces ...

A controversial new proposal for .NET suggests the introduction of a limited form of multiple inheritance via abstract interfaces. This feature was inspired by Java’s default methods.