What exactly is “interface based programming”?

Question

I often hear/read about interfaced based programming but I am not exactly clear on what that really means. Is interfaced based programming an actual stand alone topic that

Answer 1

This is something that I don't recommend using heavily in C# development.

Interface-based programming is basically programming to interfaces. You develop the interfaces you're going to use an Contracts, and the actual implementation of the interfaces is hidden behind these contracts.

It was very common prior to .NET, as the best way to get reusable components in Windows was via COM, which worked via interfaces everywhere. However, given .NET's ability to support multiple languages with a single runtime (the CLR), as well as it's superior support for versioning when compared with native code, the usefulness of interface based programming is lessened dramatically when you're programming in C# (unless you're trying to make COM components, in which case, you'll still be creating the COM interfaces indirectly from your C# classes).