The team’s development process defines who does what, when, and how.
Waterfall – activities proceed through a fixed sequence, each step depending on the previous one.
Spiral – starts with risk-driven prototypes, then follows a structured waterfall-like process.
Iterative – a hybrid that decouples lifecycle phases from the activities within each phase.
Whichever model you choose, build at least one early prototype to get customer feedback before committing to a full implementation.