Documentation for JIRA 5.2. Documentation for other versions of JIRA is available too.

For more articles, please see the JIRA Knowledge Base.

(warning) The information on the FAQs linked below may not apply to JIRA OnDemand.

JIRA Administrators FAQ
Performance FAQ
Usage FAQ
Installation Notes
How to display custom field of the sub-task in the parent issue screen?
How to change the font size for printing an issue
How to recover the comments viewable by a Project Role which has been deleted
How To Remove the Message 'Some issue types are unavailable due to incompatible field configuration and/or workflow associations.' from Edit Issue Screen

Also check out the JIRACOM and the Forums