[W]hen people are free to do as they please, they usually imitate one another. We look to others for information about what is right or good to do in a given situation, and this social proof shapes everything from the products we buy to the candidates we vote for. […]

If people can’t see what others are doing, they can’t imitate them. So to get our products and ideas become popular we need to make them more publicly observable. […] We need to make the private public. If something is built to show, it’s built to grow.

Jonah Berger — Contagious: Why Things Catch On