Ans. The incremental model is proposed by D.L PARNAS. It is basically implemented by combining elements of linear sequential model and iterative prototyping model. Incremental development refer to the process of developing to completion only a part of the requirement at a time by selectively developing parts of the requirements, designing, coding and testing software that means these require functions, the software product may be built up incrementally to its final configuration. This approach model releases the product partially to the customer in the beginning and slowly at increased functionality to the system. That is why it is called incremental model. The model prioritizes the system requirements and implements them and implements them in groups. Each new release of the system enhances the functionality of the previously released system thereby reducing the cost of project. In the first release on the functionality of the product is offered to the customer. In the second release, functionality A+ functionality B is offered. Finally, in release 3 functionality A, B and C are offered. Therefore with each release in addition to new functionality in the system, functionality of earlier release may also be enhanced.
Advantages of incremental Model:-
• As product is to be delivered in parts, total cost of the project is distributed.
• Limited number of persons can be put on to the project because work is to
be delivering in parts.
• As development activities for next release and use of early version of
product is done. Simultaneously, error if found can be corrected.
• Customers or end users get the chance to see the useful functionality early
in SDLC.
• As a result, of end users feedback requirements for successive release
become clearer.
• Testing also becomes easier.
• Risk of failure of product is decreased as user start using the product early.