Experiments are run on every user at some point in their tenure on the site. Whether that is seeing different size ad copy, or different marketing messages, or different call-to-action buttons, or having their feeds generated by different ranking algorithms.… The fundamental purpose of most people at Facebook working on data is to influence and alter people’s moods and behavior. They are doing it all the time to make you like stories more, to click on more ads, to spend more time on the site. This is just how a website works, everyone does this and everyone knows that everyone does this.

Shoshana Zuboff, The Age of Surveillance Cap…, loc. 940