what is JPA Persistence Unit

[Puspender Tanwar]

What is Persistence Unit in JPA? What is the use of it? I googled for it but didn't find any good explanation with example.

Also, I have got some basic understanding of JPA with Hibernate using a online video course, but I want to go more deeper, can someone please suggest me a good resource or book?  I thought of java persistence with hibernate but amazon reviews are not good. Any other book I can follow?

[Jeanne Boyarsky]

A "persistence unit" is a set of entities. For example, see this XML file.