Common Language Runtime

The .NET Framework includes a set of classes that run on top of an execution environment called the CLR. The CLR enables the following key benefits:

• Multilanguage support True to its name , the CLR is a runtime- execution environment that provides a common set of features across many different languages. Coupled with the .NET Framework classes, developers can write code in the language of their choice and not have to worry about using a different framework of classes. This arrangement is especially useful in a mixed-language environment in which some developers are coding in one language, such as C++, and others are coding in a different language, such as Microsoft Visual Basic. For example, you dont have to learn a different way to open a file just because a project is better suited to a different programming language.

• Code access security The CLR provides a means of protecting important resources on the system such as the hard disk, the network, or the user interface. Code access security in the CLR protects these resources by inspecting code as its running and only allowing the code to access a resource if it has permission . Administrators and users can decide what permissions theyre willing to grant to an application based on information associated with that application called evidence . For example, an application that is downloaded off an Internet site and runs in a browser might be able to communicate only with the host site from which it came, whereas an application installed on the local machine and run by a user might be able to send messages to other nodes on the network. In this example, the network represents the protected resource, and the location from which the application runs is used to determine the manner in which the application can access the network.

• Memory management Applications written on top of the CLR do not need to explicitly allocate and free system memory. Handling your own memory management can be complex and time consuming. In fact, memory management is one of the most common sources of bugs and security vulnerabilities in todays applications. Without having to worry about memory management, developers are able to be more productive, write more robust code, and focus on solving their own problems.

• Managed code Managed code is code that executes on top of the CLR. Its called managed code because the CLR takes care of, or manages , the codes execution, such as requests for system memory and the application of code access security policies.