Learn how to build applications for a platform that can reach 330M+ worldwide users! This session gives a technical overview of the Yahoo! Application Platform (YAP), which enables third-party applications to be embedded within popular Yahoo! destinations such as My Yahoo! and the Yahoo! home page. The session will cover key features of YAP, including Yahoo Markup Language (YML), Caja, Open Social, image cache and application editor. Next the talk will explain how to build an application for this platform as well as best practices to deliver great user experience from your application.