Internet Information Services (IIS) for Windows® Server is a flexible, secure and easy-to-manage Web server for hosting anything on the Web. From media streaming to web application hosting, IIS’s scalable and open architecture is ready to handle the most demanding tasks.

Multi-threaded application frameworks like Classic ASP and ASP.NET run efficiently inside processes called Application Pools, enabling blazing fast performance and complete process isolation between Applications. With IIS7, new Web sites and applications are automatically created within their own Application Pool, ensuring they are securely isolated by default. Application Pools are monitored for health and availability, and can be gracefully recycled in the event of memory leaks, deadlocks, and other health-related parameters.

In order to maintain a high performance, reliable, single-threaded environment for application frameworks like PHP, IIS7 includes the all-new FastCGI module, which allows Application Pools to spawn durable, single-threaded child processes for PHP requests. FastCGI processes not only maintain the single threaded environment many PHP extensions expect, but persist between requests, thereby increasing performance and providing excellent reliability.

The result: ASP.NET and PHP applications run inside IIS7 with greater performance and reliability than ever before.

The .NET Framework (pronounced dot net) is a software framework (an operating system within an operating system) that runs on Microsoft Windows.

Programs written for the .NET Framework execute in a software environment (as contrasted to hardware environment), known as the Common Language Runtime (CLR). The CLR is an application virtual machine.

To an end user, the promise of .NET is more programs available more quickly, on more platforms, with fewer problems.

A program written for .NET requires that the .NET framework must be installed before the new program can run.

.NET not only works on Windows computers, but other versions of .NET are also there. e.g Mono is open source .NET framework for other platforms like Linux, Mac OS , Portable .NET is another example of open source .NET .

.NET is not specific to computers , Compact .NET also runs on PDA, Smartphones etc.

With a CLR like .NET, programmers need not consider the capabilities of the specific CPU that will execute the program. The CLR also provides other important services such as security, memory management, and exception handling.

The Common Language Runtime (CLR) is a special run time environment that provides the underlying infrastructure for Microsoft’s .NET framework. This runtime is where the source code of an application is compiled into an intermediate language called CIL (Common Intermediate Language), originally known as MSIL (Microsoft Intermediate Language). When the program is then run, the CIL code is translated into the native code of the operating system using a just-in-time (JIT) compiler.