Real User Monitoring (RUM) tools help improve website and application performance by collecting data from actual user interactions in real time, providing insights into how users experience speed, responsiveness, and functionality across different devices, browsers, and locations. This helps teams detect performance bottlenecks, optimize page load times, and quickly identify issues that affect real users rather than just simulated environments. In my opinion, the most important metric is user experience, because it reflects the overall quality of interaction from the user’s perspective and directly impacts satisfaction and engagement. While speed and error tracking are also crucial for diagnosing technical issues, user experience provides the most meaningful view of how performance affects real-world usage and business outcomes.