Hibernate is the leading ORM (Object to relational) framework in Java world used to implement persistence layer of enterprise Java applications. It was one of the first Java frameworks on ORM persistence and exists even before the Java Persistence API was introduced. It has since then implement JPA interfaces and you can use Hibernate as one of the JPA implementation. In fact, it is one of the most popular JPA implementation in Java world. I receive a lot of email about books and tutorial to learn Hibernate, especially from intermediate Java developers, who has a couple of years of experience in Java but new to Hibernate. It is also a very useful skill to have on your resume because they are a lot of companies who are using Spring and Hibernate to developer enterprise Java application. So if you are looking for a job in Java world, particularly as Java web development role learning both Spring and Hibernate can help you to get your dream job.