Asp.net classes? can give Explanations?

Asp.Net contains collection of classes known as 'name space'  some of the name space and classes are

eg:  System.web  contains classes and interfaces that enable browser/server communication. This namespace provides classes for managing HTTP output to the client (HttpResponse) and reading HTTP requests (HttpRequest). Additional classes provide facilities for server-side utilities and processes, cookie manipulation, file transfer, exception information, and output cache control.

one class contains many method and properties,it contain static methods that we can use without create the object,one instan of class is known as object,all definition in it called members.

hi,
i would say all the classes found in following namespaces that are used for building asp.net controls and classes providing logic for state mangement, site navigation etc:
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;