This document discusses data independence and schema architecture in databases. It defines key terms like schema, subschema, and the three-schema architecture consisting of the physical, logical, and view levels. The physical level deals with how data is stored, the logical level describes what data is stored and relationships, and the view level is the user's perspective. Data independence allows changes to one level without affecting higher levels, for example storing a name field differently physically but presenting it the same logically. Examples demonstrate logical and physical data independence.