This document provides an overview of the Common Language Runtime (CLR) and how it works in the .NET framework. The CLR is the runtime environment that supports multiple programming languages by loading assemblies, managing memory, providing security and exception handling. It loads assemblies into memory and uses a just-in-time (JIT) compiler to convert the intermediate language (IL) code within assemblies into native machine code. Assemblies are the fundamental deployment and reuse units in .NET applications, taking the form of EXE or DLL files containing IL, metadata and resources.