Real user monitoring + Synthetic monitoring
Synthetic Performance Monitoring is a monitoring process initiated proactively by external agents that are meant to imitate actual end users and web traffic.
Real User Monitoring is measured while the actual users are visiting and interacting with the web application. This is a passive approach in which the initiation is done by the actual users and providing insight into the web application traffic.
Combine synthetic monitoring and real user monitoring to achieve the best insight — both can coexist in the same web application environment. As requirements vary from one business to another, and from one application to another, the best approach may be mixed.