There are different models of SDLC. We can also call them methodologies.

Among them these are the methodologies which are most frequently used in software industry.

The different models of SDLC are

1. Waterfall Model

2. Spiral Model

3. Prototype Model

4. V  Model

5. Agile Methodology

Let us discuss each model in detail.

Waterfall Model and Its Phases:

Waterfall model is one of the oldest model.

Waterfall Model is the fundamental model because from this model all other models have been developed.

Phases :

It contains all the phases that are present in the SDLC.

     1.Requirements collection.:

In this phase either BA or PA is going to collect the requirements from the customer.

     2. Feasibility Study:

In this phase a set of people sit together and decides whether the product is doable or not.

     3. Design:

In this phase blue-print of the software will be developed.

     4. Coding:

In this phase developers starts writing the code in one of the programming language.

     5. Testing:

Once the coding is completed the application is giver to the test engineers where they are going the check the functionality of each and every module and also its components which is called testing. During testing   process they may find bugs which needs to be reported to the developer and the developer fixes the bug by  making necessary code changes and he again sends it to the est engineer and test engineer retests the application. This process continues until the application is bug free.

     6. Installation:

Once the application is developed and tested it is handed over to the customer in installation phase.

     7. Maintenance:

Once the customer starts using the application he may find some issues which needs to be immediately fixed and tested and hand it over to the customer in the maintenance phase.


  • In waterfall model execution takes place sequentially ie., output of one phase is given as input to the next phase.
  • Waterfall is not flexible for changes ie., requirements are freezed at initial stages.
  • The changes in requirements occur due to Business needs have been changed (or) technology have been changed (or) customer needs have been changed.

Q) Where we use Waterfall Model ?

Ans: We use waterfall model in life critical and machine critical applications where requirements are freezed at initial levels.

Q) Why it is called waterfall Model?

Ans: Since backtracking is not possible it is called Waterfall Model.

That’s all regarding Waterfall Model. Let us see the another model in next post….