Since the 2007 launch of the iPhone, smartphones have granted billions of people customized, password-protected, hand-held access to a near-limitless array of digital stimuli. And this portable, pervasive parallel universe is highly addictive, often by design.

The leading online pornography site, Pornhub, was founded in 2007, a few months before the first iPhone dropped. By 2009, the site was already receiving millions of monthly unique visitors. In November 2022, Pornhub was visited 10.2 billion times, making it the fourth most popular destination on the web, and 97% of that traffic came from mobile devices.