The System.Xml namespace provides standards-based support for processing XML. The supported standards are: XML 1.0, XML Namespaces, XSD Schemas, XPath expressions, XSLT transformations, DOM Level 1 Core, and DOM Level 2 Core.

In addition to W3C DOM-compliant interfaces, System.Xml provides optimized pull-based readers and optimized writers. Finally, System.Xml provides an easy-to-use XML binding library (XML Serialization).

The System.Windows.Forms namespace contains classes for creating Windows-based applications that take full advantage of the rich user interface features available in the Microsoft Windows operating system.

Most classes within the System.Windows.Forms namespace derive from the Control class. The Control class provides the base functionality for all controls that are displayed on a Form. The Form class represents a window within an application. This includes dialog boxes, modeless windows, and Multiple Document Interface (MDI) client and parent windows. You can also create your own controls by deriving from the UserControl class.

The System.Web namespace supplies classes and interfaces that enable browser-server communication. This namespace includes the HttpRequest class, which provides extensive information about the current HTTP request; the HttpResponse class, which manages HTTP output to the client; and the HttpServerUtility class, which provides access to server-side utilities and processes.

System.Web also includes classes for cookie manipulation, file transfer, exception information, and output cache control.

The System.Timers namespace provides the Timer component, which allows developers to raise an event on a specified interval. The Timer component is a server-based timer, which is designed for use with worker threads in a multithreaded environment.

Server timers can move among threads, resulting in more accuracy than Windows timers in raising the event on time.