The .net framework provides a runtime environment for CLR which runs code and provides services that makes the development process easier . The compilers and tools expose the CLR functionality and enable you to write the code that benefits from this manged execution. Code that you develop language compiler that targets the runtime is called managed code.
           It benefits from features such as cross language integration , cross language exceptional handling , enhanced security and deployment support, a simplified model for component interaction to enable the runtime to provide services to managed code. Language compilers must emits meta data that describes the types , members and references in your code.
           Meta data is stored with the code. In loadable CLR portable execution file contains meta data. At runtime meta data is used for locate and load classes, layout instances in memory, resolve method invocations, generate native code, enforces, security and set runtime context boundaries.
           The runtime automatically handles object layout and manages references to objects, releasing data when they are no longer being used. Objects whose lifetimes are managed in this way are called managed data.