The United Kingdom on 25 July began enforcing the Online Safety Act, requiring pornography websites and a wide range of social-media platforms to verify that users are at least 18 years old. The rules, administered by the communications regulator Ofcom, replace self-declared age gates with mandatory checks such as government-ID uploads, credit-card validation or AI-based selfie scans. Pornhub and some 6,000 other adult sites have signalled compliance, while mainstream services including Reddit, Bluesky, X and Grindr now block unverified U.K. users from viewing adult material or, in some cases, from using direct messages. Companies that fail to introduce what Ofcom calls “highly effective” checks face penalties of up to £18 million or 10 percent of global turnover, and persistent offenders risk being blocked at the network level. Early data suggest determined users are looking for work-arounds: technology firms tracking web traffic reported a 1,400 percent surge in U.K. virtual-private-network sign-ups, and researchers have documented efforts to spoof the systems with AI-generated IDs or images of video-game characters. Civil-liberties groups warn the regime could chill lawful speech and expose sensitive personal data, while Ofcom counters that age assurance is necessary to curb children’s exposure to pornography, self-harm material and other harmful content. The British rollout comes as other jurisdictions weigh similar measures. Four days before the U.K. rules took effect, U.S. trade association NetChoice asked the Supreme Court to block a Mississippi law that imposes age-verification and parental-consent requirements on social-media services, arguing it violates constitutional free-speech protections. Lawmakers in France, Ireland and Australia are also moving toward mandatory online age checks, signalling a broader shift toward an age-gated internet.