Study finds over one-third of new webpages show AI authorship

The web is being rewritten, quite literally, by machines. A peer-reviewed study from researchers at Imperial College London, Stanford University, and the Internet Archive found that roughly 35% of newly published websites by mid-2025 can be classified as AI-generated or AI-assisted. More than 20% are fully AI-generated, with no meaningful human editing detected. That figure was effectively zero before ChatGPT’s public launch in late November 2022. In about two and a half years, AI went from writing none of the web to writing more than a third of its new pages. What the data actually shows The research team, led by Jonas Dolezal, Sawood Alam, Mark Graham, and Maty Bohacek, analyzed a stratified sample of websites archived through the Wayback Machine from mid-2022 to mid-2025. They used the Pangram v3 detector to classify content, scanning for linguistic patterns characteristic of large language model output. Two findings stood out. AI-generated sites showed a 33% increase in semantic similarity compared to human-written pages. The second notable result: positive sentiment scores on AI-generated pages were 107% higher than on human-written ones. But the study also pushed back against...