Hibernate ORM is an object-relational mapping framework for Java and relational databases. Its own site describes it as “idiomatic persistence for Java and relational databases,” and explains that “Hibernate makes relational data visible to a program written in Java, in a natural and type-safe form, making it easy to write complex queries and work with their results, letting the program easily synchronize changes made in memory with the database, respecting the ACID properties of transactions.” The project bills itself as “the most successful ORM solution ever, in any programming language.”
The framework’s core job is the mapping described in the Data Mapper pattern: keeping in-memory Java objects and database rows in sync while keeping each independent of the other. A developer defines how classes correspond to tables, and Hibernate generates and runs the SQL needed to load, save, and query those objects, including managing transactions and lazy loading of related data.
Hibernate’s design proved widely influential. The approach it popularized became the template that many later ORMs in other languages followed, and its ideas fed directly into the Java Persistence API (JPA) standard. The project remains actively developed; its site lists a latest stable release of 7.4 and notes the framework is released under the Apache Software License v2.
Note on dating: the listed date of 2001 reflects Hibernate’s widely reported origin year, but it is not asserted from the cited primary pages above, which do not state a founding date.