In DBMS, an instance refers to the data or information stored in the database at a particular moment in time. It is also called a current state or database state. The database schema defines the attributes of the database in the particular DBMS, and the value of the particular attribute at a particular moment in time is known as an instance of the DBMS.
For example, consider a table named "Student" with the schema "Std ID", "Name", and "City". The rows in this table are called instances. If the table has 100 records today, then the instance of the database today has 100 records. If we add another 100 records to this table by tomorrow, then the instance of the database tomorrow will have 200 records in the table.
In summary, an instance in DBMS is the collection of information stored in a database at a particular moment in time, while the database schema defines the attributes of the database in the particular DBMS.
