Yahoo Application Platform (YAP) allows developers to build engaging applications that can be permanently parked in high-traffic areas on Yahoo sites, making them viral in nature. YAP apps can be quickly built using YML and have access to 600 million Yahoo users. YAP supports both small cached views and full external views. Small views are limited to HTML and YML while full views also support JavaScript, CSS, and external URLs. YAP apps can access user profile data and social graph connections through Yahoo APIs.