" Jonah Berger, a social scientist well-known for his studies of virality, explains that publicness is one of the most crucial factors in driving something’s spread. As he writes in his book Contagious, “Making things more observable makes them easier to imitate, which makes them more likely to become popular. . . . We need to design products and initiatives that advertise themselves and create behavioral residue that sticks around even after people have bought the product or espoused the idea. "

― Ryan Holiday , Growth Hacker Marketing: A Primer on the Future of PR, Marketing, and Advertising