PostHog Recorder is a client-side JavaScript library that enables websites to capture detailed user interactions and DOM changes for session replay. It records events such as clicks, scrolls, form inputs, and page navigation, allowing product teams to visually reconstruct and replay user sessions. This data is then sent to the PostHog platform, where it can be analyzed to understand user behavior, identify usability issues, and debug front-end problems. The script observes mutations to the Document Object Model (DOM) and captures various user events to provide a comprehensive visual playback experience. It integrates seamlessly with other PostHog analytics features, providing a holistic view of the user journey. The recorder can also be configured with privacy settings to mask sensitive data before it is transmitted. This script runs in the user's browser, continuously monitoring and capturing activity. It then bundles this information and sends it to PostHog's backend infrastructure for storage and processing. This allows developers and product managers to understand how users interact with their application in real-time and retrospectively, helping to improve user experience and product design.