Three most commonly used methodologies are

1. Waterfall model-Development goes on for 4, 5 months. When whole product is developed only then it is handed over to testers to test.If bugs are found developers fix it.

Disadvantage of waterfall model Is if there is a core problem with the project like there is a major bug It may 1, 2 months to fix it as fixing this bug can affect the whole code as whole code need to be iterated.

Steps in Waterfall Model are-

1. Requirement spectifiation-The requirements are gathered from user in req. phase

2. Functional Specification-Defining the functions for those requirements.

3. Program Specification

4. Coding

5. Testing