# Schema & Instance

## Schema

* A schema is a description of the data interface to the database (i.e. how the data is organized).
* Schema is the overall design of a database.
* It is the skeleton structure of the database.
* It represents the logical view of the entire database.
* A schema contains schema objects:- table, columns, data types, foreign key, primary key, views, stored procedure, etc.
* It represents database objects and relationships with visual diagrams.
* It is designed by database designers to help programmers.
* The process of database creation is called data modeling.
* A schema diagram can display only some aspects of a schema like the name of record type, data type, and constraints. Other aspects can't be specified through the schema diagram.

## Instance

* A database instance is a database (real data) that conforms to a given schema.
* Data at a particular moment of time is called the instance of the database.