Load testing is the process of putting demand on a system or device and measuring its response. Load testing is performed to determine a system's response under both normal and anticipated maximum load conditions identifying the maximum operating capacity of an application as well as causing any material degradation. When a load is placed on a system and it is raised beyond normal usage patterns, in order to test the system's response at unusually high or maximum load conditions. Load testing or load analysis is sometimes referred to as stress testing, a load is usually so great that error conditions are the expected result, although no clear boundary exists when an activity ceases to be a load test and becomes a stress test.

There is little agreement on what the specific goals of load testing are. The term is often used when discussing the reliability and durability of an unproven product or material.