Waterfall Model: Introduction and Working on Waterfall Model

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Topics to be Covered

Topics to be Covered

Introduction on Waterfall Model

  • This waterfall model was introduced in 1970 by Winston Boyce. It is a kind of sequential model where phases or steps are already pre-defined and each phase is designed to follow some function that is required to achieve the goal that is development of system or software.
  • It is used in software development processes in which progress can be seen in every phase. It considers various phase like conceptualization, initialization, Design, Development, Testing, Production and Updation or Maintenance in the last.
  • The most important thing about this model is that a phase takes place in sequential order as predefined manner and cannot be backed as per requirement.
  • Each step needs to be completed before going to next step.

Working of Waterfall Model

  • If once, steps implemented cannot return to previous results.
  • It is non-iterative sequential and linear model which is used for software development. It follows top-down approach.
Working of Waterfall Model


  • Earliest Model (Classic Life Cycle Model)
  • Sequential Model (Linear Cycle Life Cycle Model)
  • Every phase must be implemented and completed before going to start the next step or phase
  • It is easy to understand and implement the process
  • It can be used, if requirements are already very well defined (Pre-defined)
  • Requirements of customer must be clear and must not be ambiguous.
  • Helpful in short Project/assignment having small budget.
  • Less risk in this model.

Advantages of Waterfall Model

  • Easy to manage and understand.
  • Well understood stages and can be complemented and integrated easily.
  • Straight forward model.
  • The Project which are having short span time can be developed in better quality.
  • As, we do paperwork in this model, thus, while implementing we have lot of material to refer and execute the project in Proper manner.

Disadvantages of Waterfall Model

  • No working software is produced until late during the life cycle.
  • Uncertainty for big budgets.
  • Object Oriented Projects cannot be implemented
  • Within stage or intermediatory phase, we cannot measure the progress of the project and cannot be shown to the customer until complete project is ready and tested completely.
  • Modifications cannot be added in the later stages, if customer requires.
  • The testing time comes quite later. That is against the principle of software testing.
  • Prior resource allocation.
  • Communication gap can result in big problems.


Q. 1. : Which of the following is not the step or phase under Waterfall Model.

i. Feasibility Study

ii. Requirement Analysis & Defining

iii. Coding & Unit Testing

iv. Deployment

v. Integration and System Testing

Choose the Correct Options:

(1) i only

(2) i and ii only

(3) v only

(4) None of the above

Answer: (4) None of the above

Q. 2. : What do you understand by the term ‘Requirement Analysis’ in ‘Waterfall Model’ ?

(1) All possible requirements of the system to be developed

(2) All requirements need to be orally explained to the developer

(3) All steps need to be written on paper and must be followed in sequential order

(4) All of the above are correct

Answer: (1) All possible requirements of the system to be developed

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