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

In conclusion, when you use a local variable of a type that implements IDisposable, always, without exception, use using¹.

If you use nonlocal IDisposable variables, then always implement the IDisposable pattern.

Two simple rules, no exception¹. Preventing resource leaks otherwise is a real pain in the *ss.

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¹⁾: The only exception is – when you're handling exceptions. It might then be less code to call Dispose explicitly in the finally block.