The Mono scripting backendA framework that powers scripting in Unity. Unity supports three different scripting backends depending on target platform: Mono, .NET and IL2CPP. Universal Windows Platform, however, supports only two: .NET and IL2CPP. More info
See in Glossary compiles code at runtime, with a technique called just-in-time compilation (JIT). Unity uses a fork of the open source Mono project.
Some platforms don’t support JIT compilation, so the Mono backend doesn’t work on every platform. Other platforms support JIT and Mono but not ahead-of-time compilation (AOT), and so can’t support the IL2CPP backend. When a platform can support both backends, Mono is the default. For more information, see Scripting restrictions.
Mono supports the debugging of managed code. For more information, see Debugging C# code in Unity.
You can change the scripting backend Unity uses to build your application in one of two ways:
To start the build process, open the Build Settings window (Menu: File > Build Settings) and select Build.
Both the Mono and IL2CPPA Unity-developed scripting back-end which you can use as an alternative to Mono when building projects for some platforms. More info
See in Glossary scripting backends require a new build for each platform you want to target. For example, to support both the Android and iOSApple’s mobile operating system. More info
See in Glossary platforms, you need to build your application twice and produce two binary files, one for Android and one for iOS.