Web applications are a collection of resources on a publicly accessible server that provide some sort of functionality. Users access them by using a Web browser, which is responsible for downloading any code needed for the Web application, interpreting the code, and displaying the results to users. The standard types of files you create when building a Web application are Hypertext Markup Language (HTML), Cascading Style Sheets (CSS), and JavaScript files. Taken together, these types of files enable you to build powerful Web applications.
Generally, smartphones are capable of rendering pages intended for the desktop with no problems, and the devices covered in this book have excellent browsers that can render Extensible HTML (XHTML) with CSS and run JavaScript code. Both iOS and Android devices use the WebKit browser engine. WebKit is an open-source rendering engine developed by Apple as a derivative of the Linux Konqueror browser’s KHTML engine.
Windows Phone 7 devices use a version of Internet Explorer (IE), Microsoft’s Web browser. Almost any application you develop on the Web for the desktop can be rendered on a smartphone browser, with the exception of Adobe Flash content. For a number of reasons, including security and battery drain, Apple has rejected including support for any Flash content on iOS devices; instead, it targets the newest HTML 5 specification. Both Android and Windows Phone 7 support versions of Flash.