In many cases, short interval volume testing cannot expose defects in a web application. LoadStorm provides an easy way to apply a long duration test of significant volume to bring certain bugs to the attention of your QA team.

Also known as "soak testing", endurance testing has a focus on time and throughput. This type of testing normally has the objective of finding memory leaks in the application. Most people consider endurance testing as a subset of performance testing because it involves some load and some stress. The stress is similar to placing the server(s) in a low memory state (typical condition of stress testing). Memory leaks can stress your application by filling up otherwise useful memory with unnecessary data.

Formal Definition

"Soak tests are used primarily to check the reaction of a subject under test under a possible simulated environment for a given duration and for a given threshold. Observations made during the soak test are used to improve the characteristics of the subject under test further." As found on Wikipedia.

Endurance testing applies volume over a significant period of time in order to discover how the system responds during sustained load. It is common for a web application
to behave as expected under load for a 30 minutes, but when tested for 5 hours certain memory or CPU issues begin to appear. Memory leaks tend to have a cumulative effect and will cause the system to fail when enough garbage is left uncollected.

As unwanted data from memory leakage consumes a large enough portion of system resources, the application will probably begin to behave in a random fashion. Memory leaks make bad things happen - and the bad things are usually hard to replicate. Inconsistent bugs are the hardest to resolve, so endurance testing becomes that much more important.
Try LoadStorm for your web endurance testing tool.