The PDF contains a glossary of over 400 techniques, including explanations of obscure abilities:
A unique component of Databook 4 is the inclusion of the sealed chapter manuscript. This section provides rare insight into the creative process of Masashi Kishimoto. It shows:
Details on the Five Great Shinobi Villages, the Shinobi Alliance's 80,000-man power graph, and the history of clans like the Uzumaki and Otsutsuki.
If you're looking for information online, you can try:
Many links claiming to be a "direct PDF download" lead to malware or broken pages. However, legitimate scanned copies do exist in private archive circles. They are usually named and are shared via Mega or Mediafire by preservationists.