A quickstart-style guide with tutorials. See also the Obtaining Hibernate section discussing the Hibernate artifacts and how to obtain them.
Migration guide covering migration from 4.3 to 5.0
Guide covering most user facing concepts and APIs of Hibernate
Guide covering mapping an application domain model
Guide covering topics of interest for developers looking to develop integrations with Hibernate.
The Hibernate Javadocs
The JPA (2.1) Javadocs
The FAQ
Wiki hosted at GitHub
Old wiki hosted at JBoss.org. Mostly out-of-date content.