This type of question is known as an operational question, which differs from a technical question. By asking this, the interviewer is expecting you to describe a process rather than provide a definition. The question still seeks to explore your knowledge of application development, but in this case, they are looking to see if you know how to complete a specific task. Organize your answer in a logical and sequential framework, and include the purpose or benefit of performing the task.

"Load testing is performed by running an application on multiple systems or devices simultaneously. Its purpose is to determine how the application functions under a load and if there is any degradation in the application's performance. An example of a load test is to launch the application simultaneously on several systems with requests for the same data using popup screens. The time required to retrieve and display the data is then compared to that of a single instance of the same process."