.NET Framework Versions and Dependencies
Each version of the .NET Framework contains the common language runtime (CLR), the base class libraries, and other managed libraries. This topic describes the key features of the .NET Framework by version, provides information about the underlying CLR versions and associated development environments, and identifies the versions that are installed by the Windows operating system.
The following illustration summarizes the version history and identifies the versions that are installed by Windows.
Each new version of the .NET Framework retains features from the previous versions and adds new features. The CLR is identified by its own version number. Some versions of the .NET Framework include a new version of the CLR, but others use an earlier version. For example, the .NET Framework 4 includes CLR 4, but the .NET Framework 3.5 includes CLR 2.0. (There was no version 3 of the CLR.) Although the .NET Framework 4.5 is an in-place update of the .NET Framework 4, the underlying CLR version number is referred to as CLR 4.5.
In general, you should not uninstall any versions of the .NET Framework that are installed on your computer, because an application you use may depend on a specific version and may break if that version is removed. You can load multiple versions of the .NET Framework on a single computer at the same time. This means that you can install the .NET Framework without having uninstall previous versions. For more information, see Getting Started with the .NET Framework.
The .NET Framework versions 2.0, 3.0, and 3.5 are built with the same version of the CLR (CLR 2.0). These versions represent successive layers of a single installation. Each version is built incrementally on top of the earlier .NET Framework versions. It is not possible to run versions 2.0, 3.0, and 3.5 side by side on a computer. When you install the .NET Framework 3.5 SP1, you get the 2.0 and 3.0 layers automatically. However, the .NET Framework 4 ends this layering approach. Starting with the .NET Framework 4, you can use in-process side-by-side hosting to run multiple versions of the CLR in a single process. Apps that were built for versions 2.0, 3.0, and 3.5 can all run on version 3.5, but they will not work on version 4 or later.
The .NET Framework 4.5 is an in-place update that replaces the .NET Framework 4 on your computer. After you install this update, your .NET Framework 4 apps should continue to run without requiring recompilation. However, some changes in the .NET Framework may require changes to your app code. For more information, see App Compatibility in the .NET Framework 4.5 before you run your existing apps in the .NET Framework 4.5. For more information about installing the current version, see Installing the .NET Framework 4.5. For information about support for the .NET Framework, see Microsoft .NET Framework Support Lifecycle Policy on the Microsoft Support website.
You do not have to install previous versions of the .NET Framework or the CLR before you install the latest version.
The following table correlates .NET Framework, CLR, and Visual Studio versions and provides a brief review of each version. Note that Visual Studio provides multi-targeting, so you are not limited to the version of the .NET Framework that is listed.
|
.NET Framework version |
Introduced with IDE |
Description |
|---|---|---|
|
1.0 |
Visual Studio .NET |
Contained the first version of the CLR and the first version of the base class libraries. |
|
1.1 |
Visual Studio .NET 2003 |
Included updates to ASP.NET and ADO.NET. This version was subsequently updated twice, with Service Pack 1 (SP1) and SP2. This version also introduced side-by-side execution, which enables apps on a single computer to run against multiple versions of the CLR. |
|
2.0 |
Visual Studio 2005 |
Introduced a new version of the CLR with additions to the base class libraries, including generics, generic collections, and significant additions to ASP.NET. This version was updated with SP1 and SP2. |
|
3.0 |
Visual Studio 2005 |
This version is essentially .NET Framework 2.0 with the addition of Windows Presentation Foundation (WPF), Windows Communications Foundation (WCF), Windows Workflow Foundation (WF), and CardSpace. It was updated with SP1 and SP2. |
|
3.5 |
Visual Studio 2008 |
Added new features such as AJAX-enabled websites and LINQ. The SP1 update added Dynamic Data, and a small set of additional enhancements. |
|
4 |
Visual Studio 2010 |
Included a new version of the CLR, expanded base class libraries, and new features such as the Managed Extensibility Framework (MEF), dynamic language runtime (DLR), and code contracts. |
|
4.5 |
Visual Studio 2012 |
Includes an updated version of the CLR, support for building Windows Store apps, and updates to WPF, WCF, WF, and ASP.NET. |
Some versions of the .NET Framework are installed automatically with the Windows operating system, but other versions must be installed separately. The following table identifies the installed and supported versions of the .NET Framework for client operating systems.
|
Client operating system |
Includes |
You can also install |
|---|---|---|
|
Windows 8 |
.NET Framework 4.5 |
.NET Framework 3.5 SP1 (see Installing the .NET Framework 3.5 on Windows 8) |
|
Windows 7 |
.NET Framework 3.5 SP1 |
.NET Framework 4.5, .NET Framework 4 |
|
Windows Vista SP2 |
.NET Framework 3.0 SP2 |
.NET Framework 4.5, .NET Framework 4, .NET Framework 3.5 SP1 |
|
Windows XP Professional and Windows XP Home Edition |
— |
.NET Framework 4, .NET Framework 3.5 SP1, .NET Framework 2.0 SP2 |
The following table provides similar information for server operating systems.
|
Server operating system |
Includes |
You can also install |
|---|---|---|
|
Windows Server 2012 |
.NET Framework 4.5 |
.NET Framework 3.5 SP1 |
|
Windows Server 2008 R2 |
.NET Framework 2.0 SP2 (enabled by default), .NET Framework 3.5 SP1*, .NET Framework 3.0 SP2* |
.NET Framework 4.5, .NET Framework 4 |
|
Windows Server 2008 SP2 |
.NET Framework 2.0 SP2 (enabled by default), .NET Framework 3.0 SP2* |
.NET Framework 4.5, .NET Framework 4, .NET Framework 3.5 SP1 |
|
Windows Server 2003 |
.NET Framework 2.0 SP2 |
.NET Framework 4, .NET Framework 3.5 SP1, .NET Framework 3.0 SP2 |
See .NET Framework System Requirements for a complete list of supported operating systems. The versions marked with * can be enabled through the Server Manager.
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If you're new to the .NET Framework, see the overview for an introduction to key concepts and features.
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For new features and improvements in the .NET Framework 4.5, see what's new.
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For information about migrating your app from the .NET Framework 4 to the .NET Framework 4.5, see the migration guide.
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For information about determining which versions or updates are installed on a computer, see How to: Determine Which .NET Framework Versions Are Installed and How to: Determine Which .NET Framework Updates Are Installed.
