Usage of interfaces in companies C#

Question

How is it? Are interfaces useful in companies (10 people groups). For example IConntect interface is needed to implement necessary methods for connect databases. Or there are some other ways to communicate between programmers in machine code? How are your feelings about interfaces as a CONTRACT in programing?

Thanks a lot

Answer 1

of course it is the way to "communicate" with other programmers because you understand what this guy wants from you.
He created interface with some methods. And its the best way to say you about his thoughts about this interface.

Answer 2

I've kept away behaviour I can invoke at will upon any Type I choose. That's power, I don't have to define types, I only need to implement it.