Mono是一个由Xamarin公司（先前是Novell,最早为Ximian）所主持的自由开放源码专案。该专案的目标是创建一系列符合ECMA标准（Ecma-334和Ecma-335）的.NET工具，包括C#编译器和通用语言架构。与微软的.NET Framework（共通语言运行平台）不同，Mono项目不仅可以运行于Windows系统上，还可以运行于Linux，FreeBSD，Unix，OS X和Solaris，甚至一些游戏平台，例如：Playstation 3，Wii或XBox 360。Mono的标志是一个猴子格式的脸。

Mono is a free and open source project led by Xamarin, a subsidiary of Microsoft (formerly by Novell and originally by Ximian) to create an Ecma standard-compliant, .NET Framework-compatible set of tools including, among others, a C# compiler and a Common Language Runtime. The logo of Mono is a stylized monkey's face, mono being Spanish for monkey.