In Detail Using Facebook Applications, developers can add custom features to one of the most popular websites in the world. Facebook is the biggest social network among college students, and is gaining ground among professionals too. Facebook applications enable you to add new ways for users to interact with each other using Facebook. Facebook applications are written in a server-side language, and hosted on the application developer's own server. They interface with Facebook, so that they appear to users to be part of Facebook itself. This book shows PHP developers how to quickly get started building powerful Facebook applications, how to work with data stored in Facebook, including photos, and how to handle multimedia and other custom data within Facebook applications. The book covers how to send notifications and invitations from within an application, update a user's profile, create application control panels for users, and much more. What you will learn from this book? Learn Facebook application development through step-by-step examples.Build data-driven Facebook applications, work with friends lists, photo galleries, multimedia, and more.Work with Facebook's security model to produce applications that are safe and functional.Communicate with users through newsfeeds, notifications, invitations, and messages.Learn the Facebook PHP API, and the various markup languages you'll need to build Facebook applications: Mock Ajax, FBML, FBJS (a variant of JavaScript especially for Facebook), and FQL. Approach This book builds on your knowledge as a PHP developer to provide a fast-paced, step-by-step tutorial in building Facebook applications. The book is packed with example code and demo applications, so that you can see techniques in action. Along the way we provide quick references to the most important aspects of the API, so you can refer back as you develop your own applications with the book. Who this book is written for? This book is for PHP5 developers who want to create custom Facebook applications. It assumes no knowledge of the Facebook API or Platform, but does assume that you are a Facebook user.