The .NET Framework class library is a library of classes, interfaces, and value types that provide access to system functionality. It is the foundation on which .NET Framework applications, components, and controls are built. The namespaces and namespace categories in the class library are listed in the following table and documented in detail in this reference. The namespaces and categories are listed by usage, with the most frequently used namespaces appearing first.
Namespaces
System
The System namespace contains fundamental classes and base classes that define commonly used
value and reference data types, events and event handlers, interfaces, attributes, and processing exceptions.
System.Activities
The System.Activities namespaces contain all the classes necessary to create and work with activities in Window Workflow Foundation.
System.AddIn
The System.AddIn namespaces contain types used to identify, register, activate, and control addins, and to allow add‐ins to communicate with a host application.
System.CodeDom
The System.CodeDom namespaces contain classes that represent the elements of a source code document and that support the generation and compilation of source code in supported programming languages.
System.Collections
The System.Collections namespaces contain types that define various standard, specialized, and generic collection objects.
System.ComponentModel
The System.ComponentModel namespaces contain types that implement the run‐time and design‐time behavior of components and controls. Child namespaces support the Managed Extensibility Framework ﴾MEF﴿, provide attribute classes that define metadata for ASP.NET Dynamic Data controls, and contain types that let you define the design‐time behavior of components and their user interfaces.
System.Configuration
The System.Configuration namespaces contain types for handling configuration data, such as data in machine or application configuration files. Child namespaces contain types that are used to configure an assembly, to write custom installers for components, and to support a pluggable model for adding functionality to, or removing functionality from, both client and server applications.
System.Data
The System.Data namespaces contain classes for accessing and managing data from diversesources. The top‐level namespace and a number of the child namespaces together form the ADO.NET architecture and ADO.NET data providers. For example, providers are available for SQL Server, Oracle, ODBC, and OleDB. Other child namespaces contain classes used by the ADO.NET Entity Data Model ﴾EDM﴿ and by WCF Data Services.
System.Deployment
The System.Deployment namespaces contain types that support deployment of ClickOnce applications.
System.Device.Location
The System.Device.Location namespace allows application developers to easily access the computer's location by using a single API. Location information may come from multiple providers, such as GPS, Wi‐Fi triangulation, and cell phone tower triangulation. The System.Device.Location classes provide a single API to encapsulate the multiple location providers on a computer and support seamless prioritization and transitioning between them. As a result, application developers who use this API do not need to tailor applications to specific hardware configurations.
System.Diagnostics
The System.Diagnostics namespaces contain types that enable you to interact with system processes, event logs, and performance counters. Child namespaces contain types to interact with code analysis tools, to support contracts, to extend design‐time support for application monitoring and instrumentation, to log event data using the Event Tracing for Windows ﴾ETW﴿ tracing subsystem, to read to and write from event logs and collect performance data, and to read and write debug symbol information.
System.DirectoryServices
The System.DirectoryServices namespaces contain types that provide access to Active Directory from managed code.
System.Drawing
The System.Drawing parent namespace contains types that support basic GDI+ graphics functionality. Child namespaces support advanced two‐dimensional and vector graphics functionality, advanced imaging functionality, and print‐related and typographical services. A child namespace also contains types that extend design‐time user‐interface logic and drawing.
System.Dynamic
The System.Dynamic namespace provides classes and interfaces that support Dynamic Language Runtime.
System.EnterpriseServices
The System.EnterpriseServices namespaces contain types that define the COM+ services architecture, which provides an infrastructure for enterprise applications. A child namespace supports Compensating Resource Manager (CRM), a COM+ service that enables non‐transactional objects to be included in Microsoft Distributed Transaction Coordinator ﴾DTC﴿ transactions. Child namespaces are described briefly in the following table and documented in detail in this reference.
System.Globalization
The System.Globalization namespace contains classes that define culture‐related information, including language, country/region, calendars in use, format patterns for dates, currency, and numbers, and sort order for strings. These classes are useful for writing globalized (internationalized) applications. Classes such as StringInfo and TextInfo provide advanced globalization functionalities, including surrogate support and text element processing.
System.IO
The System.IO namespaces contain types that support input and output, including the ability to read and write data to streams either synchronously or asynchronously, to compress data in streams, to create and use isolated stores, to map files to an application's logical address space, to store multiple data objects in a single container, to communicate using anonymous or named pipes, to implement custom logging, and to handle the flow of data to and from serial ports.
System.Linq
The System.Linq namespaces contain types that support queries that use Language‐Integrated
Query (LINQ)
This includes types that represent queries as objects in expression trees.
System.Management
The System.Management namespaces contain types that provide access to management information and management events about the system, devices, and applications instrumented to the Windows Management Instrumentation ﴾WMI﴿ infrastructure. These namespaces also contain types necessary for instrumenting applications so that they expose their management information and events through WMI to potential customers.
System.Media
The System.Media namespace contains classes for playing sound files and accessing sounds provided by the system.
System.Messaging
The System.Messaging namespaces contain types that enable you to connect to, monitor, and administer message queues on the network and to send, receive, or peek messages. A child namespace contains classes that can be used to extend design‐time support for messaging classes.
System.Net
The System.Net namespaces contain classes that provide a simple programming interface for a number of network protocols, programmatically access and update configuration settings for the System.Net namespaces, define cache policies for web resources, compose and send e‐mail, represent Multipurpose Internet Mail Exchange ﴾MIME﴿ headers, access network traffic data and network address information, and access peer‐to‐peer networking functionality. Additional child namespaces provide a managed implementation of the Windows Sockets ﴾Winsock﴿ interface and provide access to network streams for secure communications between hosts.
System.Numerics
The System.Numerics namespace contains numeric types that complement the numeric primitives, such as Byte, Double, and Int32, that are defined by the .NET Framework.
System.Printing
The System.Printing namespaces contain types that support printing, that provide access to the properties of print system objects and enable rapid copying of their property settings to another object of the same type, and that support the interconversion of managed System.PrintTicket objects and unmanaged GDI DEVMODE structures.
System.Reflection
The System.Reflection namespaces contain types that provide a managed view of loaded types, methods, and fields, and that can dynamically create and invoke types. A child namespace contains types that enable a compiler or other tool to emit metadata and Microsoft intermediate language (MSIL)
System.Resources
The System.Resources namespaces contain types that enable developers to create, store, and manage an application's culture‐specific resources.
System.Runtime
The System.Runtime namespaces contain types that support an application's interaction with the common language runtime, and types that enable features such as application data caching, advanced exception handling, application activation within application domains, COM interop,
distributed applications, serialization and deserialization, and versioning.
