sequential design process, rigid and linear
progress is seen as flowing steadily downwards
phases of conception, initiation, analysis, design, construction, testing, production/implementation and maintenance.
Royce's phases: requirements, analysis, design, coding, testing, operations
one should move to a phase only when its preceding phase is reviewed and verified, and there is no turning back
places emphasis on documentation (such as requirements documents and design documents)
inflexible and costly (a bug found in later phases of development costs more)