The .NET Framework is a managed execution environment for Windows that provides a variety of services to its running apps. It consists of two major components: the common language runtime (CLR), which is the execution engine that handles running apps, and the .NET Framework Class Library, which provides a library of tested, reusable code that developers can call from their own apps.
The Windows 10 May 2019 comes with .NET Framework 4.8 preinstalled.
However, some older apps may require .NET framework 3.5 to be installed to run.
This tutorial will show you different ways to install .NET Framework 3.5 online and offline in Windows 10.