These graphics represent design changes that are invisible to visitors but that dramatically speed up load times for the page.
All the sections of the cnnsi.com homepage that are enclosed in red boxes represent different graphic elements.
Overall there are two major boxes on top and bottom, with other boxes inside.
To speed up page loads, the top box loads first.
Visitors can read those stories and look at those elements as the second half of the page is downloading.
In the site's previous design, text loaded first, then graphics, for the whole page.