To simplify database administration, Oracle provides a Web-based management tool called Oracle Enterprise Manager. There are two ways that you can deploy Oracle Enterprise Manager:
You can then use a single HTML interface to manage and monitor software and hardware targets on all of your systems. Targets can include Oracle databases, application servers, Net listeners, and third-party software. This single interface is called Oracle Enterprise Manager Grid Control (or simply grid).
Oracle Enterprise Manager Database Control software is installed by default with every Oracle Database installation. This local installation provides a Web-based interface called Oracle Enterprise Manager Database Control. The Database Control is similar in function to the Grid Control, but it can manage only a single database. If you want to administer more than one database on this system, then you must either configure a separate Database Control for each database, or install Oracle Enterprise Manager 10g Grid Control.
Oracle Enterprise Manager 10g is available separately on the Oracle Enterprise Manager Grid Control installation media, and also on the Oracle Technology Network Web site at: http://www.oracle.com/technology/documentation/oem.html