In 1995 Booch and Rumbaugh began to merge their methods into a common Unified Method (UM) notation. Each of these three 'veterans' had developed his own method, each one specialized in and limited to its own area of application.

The godfathers of this idea were Grady Booch, Ivar Jacobson and James Rumbaugh. Despite the fact that the idea of object orientation is more than 30 years old, and the development of object-oriented programming languages spans almost the same length of time, the first books on object-oriented analysis and design methods didn't appear until the early 1990's.