Editor’s note: This work is part of AI Watchdog, The Atlantic’s ongoing investigation into the generative-AI industry.The Common Crawl Foundation is little known outside of Silicon Valley. For more than a decade, the nonprofit has been scraping billions of webpages to build a massive archive of the internet. This database—large enough to be measured in petabytes—is made freely available for research. In recent years, however, this archive has been put to a controversial purpose: AI companies inc...