Managed code is computer program code that executes under the management of a virtual machine, unlike unmanaged code, which is executed directly by the computer's CPU. The benefits of managed code include programmer convenience and enhanced security guarantees. The specific term managed code is particularly pervasive in the Microsoft world. Microsoft's most common languages for creating managed code are C#, Visual Basic.NET and C++/CLI.Programs in any programming language could in principle be compiled into either managed or unmanaged code. In practice, however, each programming language is typically compiled into one type. For example, the Java programming language is almost always compiled into managed code, although there are Java compilers that can generate unmanaged code (such as GNU Compiler for Java).There are many historical examples of managed code running on a virtual machine, such as UCSD Pascal utilizing p-code. Java popularized this approach with its Bytecode executed by the Java Virtual Machine. Microsoft uses managed code in its CLR virtual machine in the .NET Framework, or another similar virtual machine.Some compilers produce intermediate "pseudocode" with intention of compiling it further into target machine code, not running it within a virtual machine as managed code (see, for example, BCPL or ALGOL 68C).
pc上执行的时候由JIT（即时编译器）编译成cpu可以执行的代码，IL语言需要.NET Framework的支持，所以叫做
被托管的代码。