Newbie question - Site vs application

As I start through the documentation and build out the testdrive application, I see references to "site" within the directory structure.  Is the design intent, to have a single application within a website or multiple independent applications (blog,gallery,admin) that can be linked from a menu?

There is no strict difference between site and application. We usually treat them as the same thing, but one site or application can also have several sub-applications (e.g. blog, gallery).

The default 'SiteController' in the testdrive application is meant to contain actions that are application-wide (or site-wide), such as search, login/logout, or static pages. If you don't like it, you can change it to something else.

It is not a matter of like vs dislike, I'm just trying to gain an understanding of the best practices. 

I stepped through the testdrive, without issue changing the database from sqllite to mysql.  Then looking for the next steps of decorating the pages and integrating the application into a site.  Thus the question.

Thanks for the reply.