What is MonoDevelop?
MonoDevelop is a cross-platform IDE primarily designed for C# and other .NET languages. MonoDevelop enables developers to quickly write desktop and ASP.NET Web applications on Linux, Windows and Mac OSX. MonoDevelop makes it easy for developers to port .NET applications created with Visual Studio to Linux and Mac OSX maintaining a single code base for all platforms.
MonoDevelop is bundled with Xamarin Studio along with Xamarin iOS/Android plugins and branding. Note that a Xamarin license is only required if you develop iOS/Android projects, all other project types are free without restrictions.
As of October 2021, the GitHub repository README has been updated to say "This project has not been built nor maintained since January 2020 and has been archived".