During a test, it replaces the browser and plays a script to the Webserver. A single user license does not limit the number of users that can be simulated in a load test. A typical web site consists of many documents and graphics that contain hypertext links to one another and to documents at other sites. As the number of documents increases, it becomes more and more difficult to know which links to change when you move a document or reorganize a section of the web. This leads over time to the creation of bad links, i.e., links that no longer point to an existing document.
Bad links are the single most common defect at web sites today.
When users attempt to follow one of these links, they receive an error message. This reflects poorly on your site and may suggest that you either don't care about quality or are incapable of achieving it. This is not a message you want to send to either existing or prospective customers. In addition to static HTML documents and graphics, web sites often contain active elements with which users interact in a more complex manner. These elements typically consist of HTML forms that provide formatted input for user requests and then invoke processing at the server to satisfy these requests.