A web application is an application software that runs on a web server, unlike computer-based software programs that are run locally on the operating system of the device. These applications are accessed by the user through a web browser with an active network connection. Since they are programmed using a client–server model structure, the user is provided with services through an off-site server that is hosted by a third-party. Commonly-used web applications includes web-mail, online retail sales, online banking, and online auctions. Web sites mostly referred to as "web applications" are those which have similar functionality to a desktop software application, or to a mobile app. HTML introduced explicit language support for making applications that are loaded as web pages, but can store data locally and continue to function even if the system is offline.
Writing web applications is often simplified by the use of web application frameworks like CodeIgniter,Laravel etc. These frameworks facilitates rapid application development by allowing a development team to focus on the parts of their application which are unique to their goals without having to resolve common development issues such as user management. Many of the frameworks in use are open-source software.The use of web application frameworks can often reduce the number of errors in a program, both by making the code simpler, and by allowing one team to concentrate on the framework while another focuses on a specified use case.