Executive summaryGlobal adoption of artificial intelligence continued to rise in the second half of 2025, increasing by 1.2 percentage points compared to the first half of the year, with roughly one in six people worldwide now using generative AI tools, remarkable progress for a technology that only recently entered mainstream use.  To track this trend, we measure AI diffusion as the share of people worldwide who have used a generative AI product during the reported period. This measure is deriv...