Load testing is the process of putting demands on a software system. It can also put demands on an application or a device. It measures the response of either of those three. Load testing is done to determine how the software system, application or device, will respond under the normal load condition and anticipated peak load condition.

Load testing helps to determine the maximum degree of the operating capacity of the software system or application along with any bottlenecks and to check which element or error and bug is causing degradation of the software system or the application.

Sometimes the load levied on the software system or application is increased beyond the normal usage limits, in order to test the response and behavior of the software system at unusually high and peak loads. This kind of testing is known as stress testing. The load is usually kept so high that the expected result is nothing more than loads of errors.

Load testing is a term used with reliability testing, software performance testing, and volume testing.

Load testing can be said to refer to the practice of determining the expected usage of a software system, program or application by simulating multiple user situation in which many users are accessing the program at the same time.

The most accurate and efficient and effective load testing simulates the actual usage environment, as compared to testing the software system or application using theoretical modeling or the analytical modeling.
- Load testing allows us to measure the QOS performance quotient of any website based on the actual behavior of the customers.
- Most of the tools and frame works that are used to carry out load testing follow the procedure of the classical load testing paradigm.