Using Session State : Session Variables « Sessions « ASP.NET Tutorial

Items stored in Session state are scoped to a particular user. 
You use Session state to store user preferences or other user-specific data across multiple page requests.
Session state has no size limitations. 

Session state can represent more complex objects than simple strings of text. 

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    void Page_Load()
    {
        Session["message"] = "Hello World!";
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Session Set</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    <h1>Session item added!</h1>

    </div>
    </form>
</body>
</html>

11.3.Session Variables
	11.3.1.	Using Session State
	11.3.2.	Retrieve the value of an item that you have stored in Session state.
	11.3.3.	Sorting a DataView stored in Session state.
	11.3.4.	Save value in text box to session and read it back (VB.net/C#)
	11.3.5.	Save value to session object and read them back (VB.net)
	11.3.6.	Store user defined object in Session (C#)
	11.3.7.	Setting and retrieving objects from the Session using State Service and a base page (C#)
	11.3.8.	Setting and retrieving objects from the Session using State Service and a base page (VB)
	11.3.9.	A session-aware base page
	11.3.10.	Session counter and application counter (C#)
	11.3.11.	Session counter and application counter (VB)
	11.3.12.	Look for Variables