Introduction
(Repeating the obvious for the newer readers here.) API stands for Application Programming Interface.
SOS has three common API interfaces. These are the site, app and subapps. These are available in the form of class objects that inherit a common API interface with extended attributes and methods appropriate for each item. SOS takes this farther by exposing them through api.app for instance. This will represent the current app at all times and this makes code more portable and because the connection is automated through the Application Framework (built in to SOS) it's available, fast and a no code required to make it so on the developers part.
site
The site is the object that represents a model for interacting with the site at large.
site API
app
An app is the applications that run on a site. This could be a shopping cart, forum, blog or any other application.
app API
subapp
To make things modular we also created sub-applications. Say you wanted to have a forum administration. You want it part of the forum app but yet packaged off in it's own realm. This is what we call a subapp in SOS.
subapp API