Definition - What does Schema mean?
A schema is the structure behind data organization. It is a visual representation of how different table relationships enable the schema’s underlying mission business rules for which the database is created.
Techopedia explains Schema
In a schema diagram, all database tables are designated with unique columns and special features, e.g., primary/foreign keys or not null, etc. Formats and symbols for expression are universally understood, eliminating the possibility of confusion. The table relationships also are expressed via a parent table’s primary key lines when joined with the child table’s corresponding foreign keys.
Schema diagrams have an important function because they force database developers to transpose ideas to paper. This provides an overview of the entire database, while facilitating future database administrator work.
Oracle Database (DB) refers to schema as a user collection of database objects. The schema and user names are the same but function quite distinctly; i.e., a user may be deleted or reassigned to another user while its collection of objects (schema) within the database remains intact.