Difference between Database, instance and schema

Hi
I don't know the clear difference between database, instance and schema.. In the broad sense, everything seems to be the same. If anyone can differentiate between them with some example, that will be of great help.
Thank you.

Hi,
In Oracle, people often do use "database" and "instance" interchangeably, or together as one term: "database instance".
A "schema" is quite different. A schema is a collection of objects (such as tables, indexes or procedures). Every object belongs to exactly one schema, and every schema is a part of exactly one database. (Names may not be unique, however. For example, your database may have one schema named SCOTT, and another schema named USER1. Each of those schemas may have a table named EMP. The EMP table in the SCOTT schema, or SCOTT.EMP, is not the same as the EMP table in the USER1 schema, or USER1.EMP. A different database, my database for example, may also have schemas called SCOTT and USER1, which are completely independent of the SCOTT and USER1 in your database.)

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