What is Mono?

Mono is an open source, cross-platform implementation of a C# compiler, and a Common Language Runtime (CLR) that is binary compatible with Microsoft .NET. The Mono CLR has been ported to many platforms, including Android, most Linux distributions, BSD, OS X, Windows, Solaris, and even some game consoles, such as Wii and Xbox 360. In addition, Mono provides a static compiler that allows apps to be compiled for environments, such as iOS and PS3.

Mono for Android runs natively and provides almost all the capabilities that a typical native Android app can have. It allows developers to reuse a larger portion of the code without a major performance trade-off.