System.CodeDOM
Contains classes representing the elements and structure of a source code document.
System.ComponentModel
Implement the runtime and design-time behavior of components and controls.
System.Configuration
Supports the creation of custom installers for software components.
System.Data
Consists mostly of the classes that constitute the ADO.NET architecture, used for database connectivity.
System.Diagnostics
Supports the debugging and tracing of applications.
System.DirectoryServices
Provides access to Active Directory from managed code.
System.Drawing
Provides access to the GDI+ basic graphics functionality. More advanced functionality is provided in the System.Drawing.Drawing2D, System.Drawing.Imaging, and System.Drawing.Text namespaces.
System.Net
Provides a simple programming interface to many of the common network protocols, such as FTP and HTTP. The System.Net.Sockets namespace provides lower-level network access control.
System.Reflection
Contains classes and interfaces that provide a managed view of loaded types, methods, and fields, with the ability to create and invoke types dynamically.
System.Resources
Manages generic or culture-specific resources and resource files.
System.Security
Provides access to the underlying structure of the .NET Framework security system.
System.ServiceProcess
Supports the installation and running of Windows services. Services are long-running executables with no user interface.
System.Text
Contains classes representing ASCII, Unicode, UTF-7, and UTF-8 character encodings, as well as abstract base classes for converting blocks of characters to and from blocks of bytes, and more.
System.Threading
Provides classes and interfaces that enable multithreaded programming.
System.Timers
Provides the Timer component, which allows you to raise an event at a specific interval.
System.Web and Related Namespaces
Contains classes and interfaces that enable browser/server communication and allow you to develop ASP.NET applications and web services.
System.Xml
Provides standards-based support for processing XML content.
