C# IDisposable – Purpose of Implementing the IDisposable Interface

Garbage collection is for memory. You need to dispose of non-memory resources - file handles, sockets, GDI+ handles, database connections etc. That's typically what underlies an IDisposable type, although the actual handle can be quite a long way down a chain of references. For example, you might Dispose an XmlWriter which disposes a StreamWriter it has a reference to, which disposes the FileStream it has a reference to, which releases the file handle itself.