From Facebook Developers Wiki

I'm new to Facebook and want to understand how facebook all links together. I'm a networking guy for the past 30+ years, so I'm interested on how it all lashes together over the internet. I have read some info about facebook (facebook server, your server, a little on apps) but nothing so far tells me how it really works. I'm interested in becoming a fb developer but not sure where to start. I need some more details.