Facebook applications allow the developers to tap into the Facebook’s vast social network, now consisting of 55 million active users, meaning users who have visited Facebook in the last 30 days. The Facebook API allows the developer to use the data from the user’s profile, their friends, their photos, events, and much more. This allows the application to be sensitive to each individual user and provide a more personalized experience. All this is at your fingertips if you are familiar with PHP5 and have access to a web-server to host your application. Once you have that, it’s relatively easy to interface with Facebook and begin the journey to making your application a social beast. Aside for the social context, another great benefit to having your application developed through Facebook lies in the way the application is distributed. You no longer need to pay to advertise on the search engines and hope that users will stumble upon your product instead of the myriad of others. Instead, once you create a Facebook application and add it to your profile, there is a very good chance it’s going to start propagating through the 55 million active users. Your friends will see it on your profile and perhaps some will add it to theirs. Their friends, in turn, will notice the brand new and spiffy application and perhaps will add it to theirs. Since almost every user is connected to somebody else, pretty soon practically everybody will at least see the application. That is all well and good, but how does one go about creating the next successful Facebook application? Like stated above, all you need is a web-server equipped with PHP5 and some experience with PHP in general. Finding such a web-server is now quite easy, since many companies offer reasonable amount of storage and bandwidth for a very reasonable price. Alternatively, if you have a good Internet connection and some time on your hands, putting together a dedicated home server is also an option. That is, until the 55 million Facebook users add your application and your ISP cuts you off for overwhelming their network with requests. While you are at it, however, it might be a good idea to make sure that the web-server also provides an SQL server, such as MySQL, if the application you are planning to build is more complex than “Hello World”. Let’s say, one way or another, you now have access to a web-server loaded with PHP5, what now? Now comes the fun part, actually creating the application. The Facebook Developers web-site offers comprehensive documentation for the Facebook API, along with videos and tutorials that can get you started right away. Along with the API component, you will also find information about FQL, the Facebook Query Language. It’s based on SQL, which most people who do web development are intimately familiar with, so picking up FQL will be quick and painless. The third component, FBML, or FaceBoook Markup Language, is a no-brainer as well if you are familiar with HTML. You will have access to most HTML tags, as well as some Facebook tags that aim to make the markup portion of the application a walk in the park.