Recently, I shared a very simple look at the WordPress layout. That was really a beginners look and I wanted to find something a little more detailed because that image created as many questions as it answered.
On the Yoast blog (they have a great SEO plugin btw) they had a much more detailed breakdown in an infographic. This image is representative of how a typical WordPress theme is structured. It isn’t about page layout as much as it is about how a theme’s different parts relate to each other.
I think having a general grasp of this concept will help you understand how to set up your websites, and what templates control what area of your websites.