Did I just call The .NET Frameworks a “platform”? Did I mean development platform, or did I mean operating system? Well, the answer to these questions are “Yes I did”, and “Both”.
So let me begin to describe The .NET Frameworks. At the core of The .NET Frameworks is a component called the Common Language Runtime or CLR which is a lot like an operating system that runs within the context of another operating system (such as Windows ME or Windows 2000). This is not a new idea. It shares traits in common with the Java Virtual Machine, as well as the environments of many interpreted languages such as BASIC and LISP which have been around for decades. The purpose of a middleware platform like the CLR is simply that a common OS like Windows is often too close to the hardware of a machine to retain the flexibility or agility required by software targeted for business on the Internet. Software running on the CLR (referred to as Managed Code) is exceptionally agile!