Application development is the process and practice of developing applications using various platforms and programming languages (JAVA, .NET, RUBY, JS, C#, Python, PHP). Online application development follows a similar testing cycle than traditional desktop software. They also need to meet additional technical and functional requirements such as security, performance, accessibility or cross-browser functionality. Productivity and time to market can be significantly improved by reusing existing code and using the relevant web application frameworks. While code reuse can contribute to accelerate application development, developers with both technical and functional expertise are essential to build and to test all aspects of application development.