Synthetic monitoring and real user monitoring (RUM) are two approaches for monitoring and providing insight into web performance. RUM and synthetic monitoring provide for different views of performance and have benefits, good use cases and shortfalls. RUM is generally best suited for understanding long-term trends whereas synthetic monitoring is very well suited to regression testing and mitigating shorter-term performance issues during development. In this article we define and compare these two performance monitoring approaches.

I tend to forget how good the MDN site is. This is a great reminder.