How HttpContext.Current is visible for the whole application if it isn't static?

I really don't understand how a class like HttpContext.Current is visible (for t开发者_运维技巧he single request) to the whole web application, without be "static".

Which kind of treatment .NET do for that class?

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In class HttpContext, Current is static property

public static HttpContext Current { get; set; }

More information see: http://msdn.microsoft.com/en-us/library/system.web.httpcontext.current.aspx

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It is what is called a Singleton design pattern.

Here's a good explanation of the Singleton pattern with examples in C#