Are there any differences between the Rational Unified Process (RUP) and the Unified Process (UP)? What does "Rational" mean, in this context?

  • 1
    I thought Rational is the name of a company?
    – tp1
    Nov 17, 2011 at 20:05

1 Answer 1


The Unified Process is a generic name for a family of process models that meet a number of criteria, such as being iterative and incremental, driven by use cases, and focus on addressing risks early. It defines four project phases: Inception, Elaboration, Construction, and Transition.

The Rational Unified Process is a refinement of the Unified Process that was created by Rational Software (now owned by IBM). It uses a series of software tools along with a process framework to define how to carry out the activities needed to run a software project, yet still provides a framework for tailoring to meet an organization's (or team's) needs.

Other refinements on the Unified Process include Scott Ambler's Agile Unified Process and the Eclipse Foundation's Open Unified Process.

  • It seems I started writing my answer while you were writing yours, but I posted first (didn't get the familiar notification that another answer was up while writing). Just a clarification, wouldn't dare submit and answer saying exactly the same as another answer (and in this case less). I've deleted mine, as yours is more informative (and mine a little snarky).
    – yannis
    Nov 17, 2011 at 18:32
  • Yeah. I got the notification that there was another answer posted as I was getting the links to the AUP and OUP. I figured since I was almost done, I was just going to post it anyway.
    – Thomas Owens
    Nov 17, 2011 at 18:34
  • 2
    well, to be fair, and based on the chronology exposed in USDP by the authors of UP, first RUP was created and then UP was published as a generalization of it (anyway, it’s the same people behind both).
    – Christophe
    Jun 28, 2019 at 7:52

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