.NET Core is a new FOSS software framework from Microsoft for C#, Visual Basic, and F#. It is designed to be cross-platform, modular and apt for modern applications, as opposed to its predecessor, the .NET Framework.
If you only want to run .NET Core managed applications, install the package.
To build apps with .NET Core, installas well.
Telemetry is enabled by default but can be disabled by Environment variables
"the required library libhostfxr.so could not be found" error
Some of the dotnet SDK tools (for example libman, dotnet-watch etc.) may expect you to have the environment variable
DOTNET_ROOT pre-configured. If it's not, an error like this one could be observed: 
A fatal error occurred, the required library libhostfxr.so could not be found. If this is a self-contained application, that library should exist in [/home/my_user/.dotnet/tools/.store/microsoft.web.librarymanager.cli/1.0.172/microsoft.web.librarymanager.cli/1.0.172/tools/netcoreapp2.1/any/]. If this is a framework-dependent application, install the runtime in the default location [/usr/share/dotnet] or use the DOTNET_ROOT environment variable to specify the runtime location.
The workaround is to manually export
DOTNET_ROOT in your shell:
SDK specified could not be found
This is believed to caused by a conflict between the Mono and MSBuild SDK libs and the dotnet core ones. To fix this export the path manually in your shell (replacing the version number as necessary) e.g: