Web mini-apps sometimes referred to as Web apps come in many varieties. Some of them are stand-alone applications that do not require a browser-- for example, those that are available for such smartphones as iPhone and Android. (This is probably the largest number of apps available today.) Many of these function as desktop or device-top applications and do not require a browser to execute. Others are complete Web sites and execute their code within the browser. Still other mini-apps are plug-ins that are attached to a par- ent Web site and can only be accessed through the parent. Perhaps the most common example of these are Facebook apps. Facebook provides an extensive API definition that allows third-party developers to create many different types of games, personal apps, and even commercial apps.