What are the uses of “using” in C#?

Question

User kokos answered the wonderful Hidden Features of C# question by mentioning the using keyword. Can you elaborate on that? What are the uses of

Answer 1

Interestingly, you can also use the using/IDisposable pattern for other interesting things (such as the other point of the way that Rhino Mocks uses it). Basically, you can take advantage of the fact that the compiler will always call .Dispose on the "used" object. If you have something that needs to happen after a certain operation ... something that has a definite start and end ... then you can simply make an IDisposable class that starts the operation in the constructor, and then finishes in the Dispose method.

This allows you to use the really nice using syntax to denote the explicit start and end of said operation. This is also how the System.Transactions stuff works.