Mono is a software platform designed to allow developers to
easily create cross platform applications.  It is an open source
implementation of Microsoft's .Net Framework based on the ECMA
standards for C# and the Common Language Runtime.  We feel that by
embracing a successful, standardized software platform, we can lower
the barriers to producing great applications for Linux.

Note:
 - After installing, it's recommended to run this command
   /usr/bin/cert-sync /etc/ssl/certs/ca-certificates.crt