Before you start learning some new technology I recommend you find some good article, which make a concise overview of the technology and give several code examples. Hibernate has become the most popular ORM solution in Java development therefore it's not strange that the most vacancies require its knowledge. This article is challenging for me, because I'm going to make a basic overview of the technology and to provide a code sample with MySQL. In the end of the tutorial you can find link to example of Hibernate usage.
The term "software development" has a lot of different abbreviations, especially when we are talking about Java development. Every day, reading any IT-portal you can see something like this: EJB, JSF, GWT, JSTL, POJO, JPA... Sometimes it seems hard to keep track of all rapidly changing technologies. So today I'm going to clarify all the aspects of JPA and Hibernate.