What is the use of hibernate. Dialect property in Hibernate configuration file in Hibernate

What is the use of hibernate. Dialect property in Hibernate configuration file?

It is hibernate property that expects the api supplied sub class name of org.hibernate.dialect.Dialect class this class name will change based on the Database software and its version we use.

   Oracle 9i----à org.hibernate.Oracle9iDialect

   Oracle 10g----à org.hibernate.Oracle10gDialect

   Mysql5----à org.hibernate.dialect.Mysql5dialect