It was originally based on OS/2, which was a joint project between Microsoft and IBM. The deal fell apart, and IBM continued to market OS/2 while Microsoft renamed their version to NT.
As NT enjoyed more success than OS/2, some critics of Microsoft suggest they used their large control of the software market to force their product onto consumers' hardware over their new competitors' product.
Windows 2000 and Windows XP, despite new names, are later versions of Windows NT.