|The Scrum Guide|
The Scrum Guide is the official guide to Scrum and is required reading for everyone working with Scrum and Agile.
It is only about 19 pages of content, that contains the definition of Scrum including Scrum’s roles, events, artifacts, and the rules that bind them together. Ken Schwaber and Jeff Sutherland developed Scrum; the Scrum Guide is written by them.
A copy of The Scrum Guide can be downloaded for free from the Scrum Guides web site in many different formats and languages.