. NET is a software platform. It's a language-neutral environment for developing .NET applications that can easily and securely operate within it.
The .NET Framework has two main components: the Common Language Runtime (CLR) and the .NET Framework class library.
The Runtime can be considered an agent that manages code at execution time. Thus providing core services such as memory management, thread management, and remoting. Also incorporating strict type safety, security and robustness.
The class library is a comprehensive collection of reusable types that you can use to develop traditional command-line, WinForm (graphical user interface) applications, Web Forms and XML Web services.
The .NET Framework provides a Runtime environment called the Common Language Runtime or (CLR) that handles the execution of the code and provides useful services for the implementation of the application. CLR takes care of code management upon program execution and provides various services such as memory management, thread management, security management and other system services. The managed code targets CLR benefits by using useful features such as cross-language integration, cross-language exception handling, versioning, enhanced security, deployment support, and debugging.
Common Type System (CTS) describes how types are declared, used and managed. CTS facilitates cross-language integration, type safety, and high performance code execution. The CLS is a specification that defines the rules to support language integration. This is done in such a way, that programs written in any language (.NET compliant) can interoperate with one another. This also can take full advantage of inheritance, polymorphism, exceptions, and other features.