Object-relational database systems, a.k.a. “universal servers,” are emerging as the next major generation of commercial database system technology. Products from relational DBMS vendors including IBM, Informix, Oracle, UniSQL, and others, include object-relational features today, and all of the major vendors appear to be on course to delivering full object-relational support in their products over the next few years. In addition, the SQL3 standard is rapidly solidifying in this area. The goal of this tutorial is to explain what the key features are of object-relational database systems, review what today's products provide, and then look ahead to where these systems are heading. The presentation will be aimed at general SIGMOD audience, and should therefore be appropriate for users, practitioners, and/or researchers who want to learn about object-relational database systems.