Includes bibliographical references.

Over the last two decades, there has been an inescapable rise of anger and aggression across our planet. Hate speech has become increasingly prevalent online, Western governments are turning towards authoritarianism and populism, and extremist groups are rising across both the left and the right ends of the political spectrum. Every day, it seems, we're hearing more angry voices and fearful opinions, we're seeing more threats and frightening news, and we're reacting faster and less rationally. The cause is hidden in plain sight: for the first time, almost all of the information we consume as a species is being controlled and curated by algorithms designed to capture our emotional attention.