A system's behavior under both normal and expected peak load circumstances is tested through load testing. It helps in finding an application's maximum working capacity, any bottlenecks, and the component that is causing degradation. Load testing is a crucial part.
If you are interested in learning more about this technology then I suggest you take up this test architect master course offered by Intellipaat. This course helps you to learn all the required skills and train you as a certified software tester.