When you create a C# application, you can specify which .NET Framework you want to target your application to. In a real-world scenario, not every customer updates their servers with the latest versions when new versions of the Framework are released. Additionally, when a new version is released, some of the old features might be deprecated and newer versions of the existing features are added. In these situations, your application should not fail. So, the .NET Framework allows you to target your application to a specific version of the .NET Framework.

You can target the .NET Framework version while creating a new project using Visual Studio, or change the target framework using the property pages of the project:

Alternatively, to change the target framework version using the property pages, select an existing project, right-click on it, and then navigate to Properties:

In the Target framework drop-down menu, select your required version: