Universe

A universe is a data abstraction layer which is built with the BusinessObjects Designer tool. The universe dose not contains any data itself, it only acts as an interface. This layer is where you define your "Business Objects" [Dimensions, Measures, Details and Filters] according to your business requirements. You will need also to define a valid database connection to the database schema that you want to use to build your universe. Then you can select tables you want or create new derived tables from the existing ones. You can also create joins between tables or let the designer tool automatically detect any reference join defined in the database schema by a reference constrain. The good point is, if the schema for the data base is changed later you will not need to go through all old reports that you build to change them. Just when you change them once in universe it will be reflects in all reports.

This is a simple way to understande the roll of the universe
Database --> Schema (Tables + Columns) --> Universe (Objects [Dimentions, measures, detailes and filters]) --> report.