What is the difference between field data and lab data in Google PageSpeed Insights?

Field data captures real user experiences by collecting anonymized data from Google Chrome users who visited your site over the past 28 days. It represents actual performance metrics like Largest Contentful Paint and First Input Delay as experienced by your visitors. Lab data (or Lighthouse data), however, simulates a user visiting your page in a controlled environment with specific hardware and network conditions, such as a mid-tier mobile device on a mobile network. While both measure similar metrics, they often show different results because field data reflects real-world usage while lab data provides a standardized testing environment.