1. A product-application-solution (PAS) model for software design and development comprising: a product layer including basic product level business objects (BO) to provide a basic functionality offered by software; an application layer including application level business objects that are defined corresponding to each business domain to provide inputs for a solution required by a user and to achieve desired business requirements; and a solution layer including solution level business object to address the specific business requirement of the user and to provide a solution to meet the specific business requirement of the user; Wherein the solution level business object is created using the application level business objects which is in turn created using the product level business objects and the solution layer is built on the application layer which is configured and customized to provide solution to meet the specific business requirement of the user.