A database schema is a blueprint or structure of a database that outlines how data is organized and structured. It describes the logical and visual configuration of the entire relational database, including tables, fields, data types, and the relationships between these entities. A schema can contain formulas representing integrity constraints specifically for an application and the constraints specifically for a type of database, all expressed in the same database language. In a relational database, the schema defines the tables, fields, relationships, views, indexes, packages, procedures, functions, queues, triggers, types, sequences, materialized views, synonyms, database links, directories, XML schemas, and other elements.

A database schema is considered the “blueprint” of a database which describes how the data may relate to other tables or other data models. However, the schema does not actually contain data. A sample of data from a database at a single moment in time is known as a database instance. It contains all the properties that the schema describes as data values.

Database schema design is also known as data modeling. Developers plan a database schema in advance so they know what components are necessary and how they will connect to each other. A database schema is owned by a database user and has the same name as that user. Each user owns a single schema, and schema objects can be created and manipulated with SQL.

Some key benefits of database schemas include ensuring data has consistent formatting, all entries have a primary key, and important data is not excluded. A well-designed schema makes it easier for users to access and manipulate data, as they will understand its structure more easily.