For each of the display options: sort by, show, and results per page; the preferences page provides the opportunity to customize the results display. When clicking the 'Save Preferences' button that saves these preferences in a cookie. These preferences will be persistent across sessions.
Checking this checkbox shows the web address (i.e. URL) for the page or document that is being shown in the search result set. Unchecking the checkbox will hide the web address in the search result set.