.NET provides a new API, new functionality, and new tools for writing Windows and Web
applications, components, and services in the Web age.
Why do we need a new API?
The Windows API, the library of functions used to write
Windows applications, was originally written in C and has steadily grown over the years. It now consists of many thousands of routines and has several problems.
First, it has grown very large and has no coherent internal organization, which can make it hard to use. During
its growth, features were added piecemeal, so it doesn’t always present a unified interface to developers, and it contains a lot of legacy functions and data types.
Second, a more major problem is that the Windows API was initially designed for use by C programmers. This means that it can be difficult to use in languages other than C, and
it also doesn’t fit in very well with modern object-oriented programming methods and languages.