How I can use a Session for a long time in my ASP.NET Application

[vusinguidge]

I have a ASP.NET Application where I use Sessions. In this Session I get the language for Example. Example:\[code\]Session["language"] = language; \[/code\]And in a other Area in my Code I use then...\[code\]language = Session["language"].toString();\[/code\]It works fine but the user had open the Browser about a feu Hours in the Background with the Application then the Session don't work Why it doesn't work and how I can solve this Problem.