IL2CPP (Intermediate Language To C++) is a Unity-developed 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 which you can use as an alternative to Mono when building projects for various platforms. When building a project using IL2CPP, Unity converts IL code from scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary and assemblies to C++, before creating a native binary file (.exe, apk, .xap, for example) for your chosen platform. Some of the uses for IL2CPP include increasing the performance, security, and platform compatibility of your Unity projects.
For more information about using IL2CPP, refer to the The Unity IL2CPP blog series and the following Unity Manual pages.
See the Scripting Restrictions page for details about which platforms support IL2CPP.
IL2CPP supports debugging of managed code in the same way as the Mono scripting backend.
• 2018–05–15 Page amended with limited editorial review