This chapter describes several conceptual database design languages from several perspectives and in sufficient detail so that a Database administrators (DBA), who must know the strengths and weaknesses of each design language, can use them to construct a conceptual schema that meets the needs of the database user. The conceptual schema describes data stored in a database to reflect a collection of real-world objects and relationships. It defines the names of objects in a database and the relationships in which the objects may participate. Basic to every conceptual database design language are the concepts of entity and entity set. Entity-relationship diagrams and relational diagrams receive a high rating because it is possible to comprehend the significant aspects of a conceptual schema by quickly examining the diagrams. DBAs frequently use the process of normalization to break apart a table that represents multiple entity sets and structure the attributes into multiple tables.