Load testing is end-to-end performance testing under anticipated production load, which determine response times for various time critical transactions and business processes.
As per wikipedia:
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 behavior under both normal and anticipated peak load conditions. It helps to identify the maximum operating capacity of an application as well as any bottlenecks and determine which element is causing degradation.