Number of likes and shares for a Facebook post are just simple aggregates that give you an idea of how popular that post was, but they don't tell you anything about how that post got so popular. For Facebook Stories, Stamen Design explored how a single post can spread through the network, via three viral photos shared by George Takei.
Each visualization is made up of a series of branches, starting from George. As each branch grows, re-shares split off onto their own arcs. Sometimes, these re-shares spawn a new generation of re-shares, and sometimes they explode in short-lived bursts of activity. The two different colors show gender, and each successive generation becomes lighter as time goes by. And the curves are just for snazz.
So you see a beautiful burst in the beginning, as the photo is shared by people who follow Takei, and then the photo spreads within smaller groups of friends. The above is from the animation that shows how a graphic for famous failures spread.