Rational Unified Process

RUP proposes that development of software be divided into cycles, each cycle delivering a fully working system. Generally, each cycle is executed as a separate project whose goal is to deliver some additional capability to an existing system (built by the previous cycle). Hence, for a project, the process for a cycle forms the overall process. Each cycle itself is broken into four consecutive
phases:
– Inception phase
– Elaboration phase
– Construction phase
– Transition phase

Figure: The RUP model.

One key difference of RUP from other models is that it has separated the phases from the tasks and allows multiple of these subprocesses to function within a phase. In waterfall (or waterfall-based iterative model), a phase within a process was linked to a particular task performed by some process like requirements, design, etc.