What is a datastore in planning CAD?

I am new to cognos enterprise planning and i would like to know what i meant by datastore in CAD.While doing a GTP in CAD we are creating a datastore in a database eg: SQL SERVER.I believe this will create a new database in SQL SERVER for that particular application.Will this database store all the planning data entered by the user in contributor webclient,if not where is the planning data stored?