A schema is a graphical representation of database structures. In Designer you create a schema for the part of the database that your universe represents.
The schema contains tables and joins. The tables contain columns that you eventually map to objects that end users use to create reports. The joins link the tables so that the correct data is returned for queries that are run on more than one table.
You design the schema in the Structure pane by selecting tables from the target database using the Table Browser. You create joins to link the tables. When you have designed the schema for your universe, you can verify the schema using an automatic integrity check.
A schema for the example Beach universe appears as follows: