Default interface methods are included in a new feature proposal for C# 8, which will allow developers to use the traits programming technique on the .NET platform.

Take advantage of default interface methods in C# 8.0 to add new methods to an interface without breaking existing implementations.

Take advantage of read-only generic interfaces such as IReadOnlyList, IReadOnlyDictionary, and IReadOnlyCollection to prevent modifications to collections in your .NET Core applications.

The IComparable interface lets you create objects that know how to sort themselves correctly. This interface also provides an example of a high-level strategy for building and extending your classes.

The proposed Default Interface Methods feature would allow a limited form of multiple inheritance in C#, F#, and other .NET languages.