The application is the last layer of OS where the developer leverages all the available components(library and SDK) and integrates them in a way to develop business logic for the targeted use cases. Application development requires in-depth knowledge of the domain, targeted use-case and good power of articulating customer’s low-level requirements. While writing the code of the application, a developer should keep security, modularity, reusability, platform independency and scalability in mind. In addition to that, it requires a study on all SW components need to be interfaced to identify what all functionality can be leveraged by APIs.