Agile Development vs Conventional Sequential Process

Sequential process (e.g. Waterfall): requirements, design, coding, testing and delivery happen once, in fixed order.
Agile: software is built in short iterations (sprints) of 1 to 4 weeks, each producing a working increment, with continuous customer involvement.

Comparison

Aspect	Agile	Conventional sequential
Iteration	Many short iterations; every cycle repeats analysis, design, code and test	Single pass through each phase; no return to earlier phases without rework
Customer participation	Continuous: customer reviews every iteration and prioritizes the backlog	Mainly at the start (requirements) and end (acceptance)
Requirement change	Welcomed, even late; changes enter the backlog for later sprints	Resisted; requirements frozen early, changes are costly
Software delivery	Frequent, working increments (every sprint)	One delivery at the end of the project
Documentation	Light; working software valued over documents	Heavy, formal, phase-wise
Risk	Found early through frequent feedback	Found late, during testing
Planning	Adaptive; plan per iteration	Detailed up-front plan
Suitable for	Changing or unclear requirements	Stable, well-understood requirements

Conclusion

Agile gives faster feedback, easier handling of change and earlier value to the customer. A sequential process gives predictability and thorough documentation, which suits fixed, stable requirements. Examples of Agile methods: Scrum, XP, Kanban.