I never had a purpose for creating a Facebook application, and I still do not. One of my friends, whose still in high school, mentioned the computer science teacher gave extra credit to any students that created a Facebook application. From my knowledge, none created one, but knowing that was what sparked interest for me to look into Facebook applications. Facebook’s APIs support all the popular programming languages but for my interest, I used PHP 5. Basically you generate and copy over the keys like any API and you type in the callback URL. The rest is pretty much you just do your own thing. You can opt to use FBML (Facebook Markup Language) or use an iframe. FBML is pretty interesting–syntax looks very similar to ASP.NET control tags.

Here is my “Hello World” Facebook application: http://apps.facebook.com/oneve-yan