There are no such thing as "global variable" in .NET. There is nothing good about "global variables", so it's only good that .NET came out without this trash. Besides, you should understand that the ASP.NET application lifetime (in terms of the code behind of a page) all lies between HTTP request and HTTP response it generates. And HTTP protocol is stateless:
http://en.wikipedia.org/wiki/HTTP[
^],
http://en.wikipedia.org/wiki/Stateless_protocol[
^].
That said, to communicate between pages, you need something to store the state anyway. For example, it could be the state stored in a database. The server-based approach is the session state management. Please start here:
http://msdn.microsoft.com/en-us/library/ms178581.aspx[
^].
—SA