Interface are alternative to multiple inheritance, Interfaces are declared using the interface keyword. It is similar to class declaration. Interface statements are public by default.
see below sample
public interface ITransactions
// interface members
An interface looks like a class, but has no implementation. The only thing it contains are declarations of events, indexers, methods and/or properties. The reason interfaces only provide declarations is because they are inherited by structs and classes, that must provide an implementation for each interface member declared.
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Editor, DotNetSpider MVM
Microsoft MVP 2014 [ASP.NET/IIS]