Unmanaged vs. Managed Code

Unmanaged executable files are binary images of x86 code loaded into memory. The role of the operating system in this case is to load the application into memory and let it run. Although there are some protections regarding memory management and I/O ports, the operating system does not have any idea what the application is doing.

By contrast, managed code is under full control of the operating system. At any point in time, the operating system can stop running the CPU and investigate the runtime state. It can also insert exception handling, array bounds and indexes, traps, garbage collection hooks, and other things. In this way, it mitigates a whole class of security concerns and typical programming errors. All programming languages that support the .NET Framework produce managed code. There are currently over 30 such languages. Several are provided by Microsoft (C#, Visual Basic .NET, managed C++, J#, JScript .NET), while others are developed by third parties (everything from COBOL to Pascal).