For many sites, the "description" field is not used when adding pages or editing page properties. Installing this addon will hide that field from the following places:
This addon works by checking if the current user is able to view the toolbar (thus indicating they are a logged-in user with permissions to add/edit pages), and if so it injects a small CSS stylesheet into the page header which hides the "Description" field and label. By simply hiding the field via CSS (as opposed to changing the core code so it never outputs the field in the first place), we ensure maximum compatibility with future updates as well as minimize the risk of data loss or php errors. Note that this CSS technique does not work in IE6 (but should work just fine on all other browsers, including IE7 and up).