Page "Windows API" Paragraph 35

Over the years, various changes and additions were made to the Windows Operating System, and the Windows API changed and grew to reflect this.

The Windows API for Windows 1. 0 supported fewer than 450 function calls, where in modern versions of the Windows API there are thousands.

However, in general, the interface remained fairly consistent, and an old Windows 1. 0 application will still look familiar to a programmer who is used to the modern Windows API.