ASP.NET session state enables you to store and retrieve values for a user as the user navigates ASP.NET pages in a Web application.

Session variables are stored in a SessionStateItemCollection object that is exposed through the HttpContext.Session property. In an ASP.NET page, the current session variables are exposed through the Session property of the Page object.

Assign value into Session

Session["User"] = "Rajesh";

Retrieve value from Session

string user = Session["User"].ToString();

Remove Particular Session

Session.Remove("User");

Assign custom object into Session

Retrieve/Convert custom object from Session

Using session for get/set like property

public static string UserName
{
get { return session["username"] as string; }
set { session["username"] = value; }
}