In the waterfall model,[5] requirements engineering is presented as the first phase of the development process.
Later development methods, including the Rational Unified Process (RUP) for software, assume that requirements engineering continues through a system's lifetime.
[6] These may include: These are sometimes presented as chronological stages although, in practice, there is considerable interleaving of these activities.
Requirements engineering has been shown to clearly contribute to software project successes.
[9] Problem structuring, a key aspect of requirements engineering, has been speculated to reduce design performance.