The Waterfall Model is a sequential software development process that consists of distinct phases: proposal definition, feasibility study, requirements analysis, system design, coding and testing, implementation, and system maintenance. It became popular in the 1970s as a structured approach to software development life cycles. Key strengths include its linear structure that is easy to understand and manage, while limitations are the inability to easily change requirements late in the process and lack of opportunity for customer feedback until full implementation. It works best when requirements are very stable and clearly defined.

1. Waterfall Model

2. Waterfall Model
SDLC approach
Became popular in 1970
Phases are organised in Linear Order
Output of one phase is input for next
phase

3. Waterfall Model Phases
 Proposal Definition
 Feasibility Study
 Requirements Analysis
 System Design
 Coding & Testing
 Implementation
 System Maintenance

4. Waterfall Model
Proposal
Definition
Feasibility Study
R
equirements
Analysis
S
ystem
Design
Coding & Testing
Implementation
System
maintenance

5. Strengths of Waterfall Model
Easy to understand, easy to use
Systematic for inexperienced staff
Milestones are well understood

6. Strengths of Waterfall Model
Sets requirements stability
Good for management control
(plan, staff, monitor, control)
Works well when quality is more
important than cost or schedule

7. Limitations-Waterfall Model
Every phase is considered as a distinct
phase
All requirements must be known before
hand
Deliverables created for each phase are
considered frozen – reduces flexibility

8. Limitations-Waterfall Model
Can give a false impression of progress
Little opportunity for customer to
preview the system (until it may be too
late)

9. Limitations-Waterfall Model
 For a new system determining requirements is
a difficult job
 So freezing requirements before design is not
practical
 Might be desirable to built only a part of it
 Later enhance as and when needed

10. Limitations-Waterfall Model
Freezing requirements requires choice
of H/W
In large projects, technology changes
when the system is completed

11. Limitations-Waterfall Model
Difficulty of accommodating change
after the process is underway
One phase has to be complete before
moving onto the next phase
Integration is one big bang at the end

12. Limitations-Waterfall Model
 Inflexible partitioning of the project into
distinct stages makes it difficult to change as
per customer requirements.
 Requirements should be well-understood so
that changes are fairly limited during the
design process

13. When to use?
Requirements are very well known
Product definition is stable
Technology is understood

14. When to use?
New version of an existing product
Porting an existing product to a
new platform.

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