Aliases are references to existing tables in a schema. An Alias is a table that is an exact duplicate of the original table (base table), with a different name.
You use aliases for two main reasons:
The example Beach universe contains 2 aliases; Resort_Country for Country, and Sponsor for Customer.
Another possible use of aliases is to create an alias for each table as it is inserted into the schema. You then build the schema using the alias tables, not the original base tables. You place the base tables together away from the main universe structure. This allows you to give meaningful names to tables, and prevents the need to rebuild major sections of a universe structure should a base table need to be aliased at a later stage.
To avoid confusing base tables with aliases, you can display the alias with the name of the base table it represents in the table title as follows: Select Tools > Options > Graphics, and then select the Aliased Name check box