Web programmers specialize in the development of World Wide Web applications or distributed network applications that are run on web servers, and accessed through a web browser. This typically requires programming on both the back-end server side, and the front-end user side. Programming the front-end involves implementing all the graphical and visual elements that users see and use in the web application, while programming the back-end requires knowledge about networking, database, web services and APIs that are necessary to power the front-end. More and more computer applications are moving to the mobile platform. Mobile programmers write programs specifically for running on mobile devices. Unlike traditional programs, mobile apps are event driven, and are limited by the resources available on mobile devices such as speed, storage and screen size. Just as with web programmers, being able to design attractive graphical interface is a plus.