Microsoft .NET Framework is the Windows runtime that many desktop programs need in order to run. The installer adds the .NET Framework runtime and associated files that are required to run – and to develop – applications that target the .NET Framework. If a program asks you to install ".NET Framework", this is the package it needs.
Latest version: .NET Framework 4.8.1. Released by Microsoft on 9 August 2022, version 4.8.1 is the newest and final major version of the .NET Framework 4 family. It replaces earlier 4.x versions such as 4.5.1, 4.6, 4.7 and 4.8, so programs written for any of those versions run on it. Since version 4.5.2, the .NET Framework is treated as a component of Windows: it stays supported as long as it is installed on a supported version of Windows.
Side by side with older versions. The .NET Framework 4 family works side by side with older Framework versions. Applications based on earlier versions continue to run on the version they target by default. Programs that need the older 2.0 or 3.0 runtime use .NET Framework 3.5 SP1, which is installed separately (on Windows 10 and 11 as an optional Windows feature) and is supported until 9 January 2029.
What the .NET Framework 4 family introduced
- Improvements in the CLR (Common Language Runtime) and the BCL (Base Class Library)
- Improvements in ADO.NET
- Enhancements to ASP.NET
- Improvements in Windows Presentation Foundation (WPF)
- Improvements to Windows Workflow Foundation and Windows Communication Foundation
About version 4.5.1. This page originally listed .NET Framework 4.5.1, released on 17 October 2013. Its support ended on 12 January 2016, so you should install 4.8.1 instead – it runs all programs made for 4.5.1.
For developers: Microsoft recommends the modern, cross-platform .NET (version 8 or later) for new projects. Install the .NET Framework only when an application you use or build requires it.