Two main reasons for measuring the web performance of a distributed application are to determine how quickly users can achieve their objectives as well as discover how a system behaves under increasing load.
The first focuses directly on the users’ experience, the second investigates underlying server behaviours, which will determine what users experience.
Measurement usually focuses on the user’s experience or on the system’s behaviour. Despite differences, these two classes of measurement activity share many technical challenges. Measurement activities and tasks may focus on a variety of possible secondary goals.