The canonical reference for scrum, first published in 2010 by ken-schwaber and jeff-sutherland and updated multiple times since. The Guide has replaced the earlier book agile-software-development-with-scrum as the authoritative definition of Scrum, and both Schwaber's scrum-org and the scrum-alliance reference it.
Publication history
The Scrum Guide has been updated at roughly three-year intervals, with each update refining and sometimes significantly changing the framework's definition:
The 2020 update was notable for removing much of the implementation guidance that had accumulated, making the Guide shorter and more principle-oriented. This reflected a long-standing tension in the Scrum community between Scrum as a defined framework and Scrum as a flexible approach.
Content
The Guide defines scrum through three pillars (transparency, inspection, adaptation — the foundation of empirical-process-control), five values (commitment, courage, focus, openness, respect), three accountabilities (Product Owner, Scrum Master, Developers), five events (sprint-planning, Daily Scrum / daily-standup, Sprint, sprint-review, retrospective), and three artifacts (Product Backlog, Sprint Backlog, Increment) each with a commitment (definition-of-done, Sprint Goal, Product Goal).
The Guide explicitly states that Scrum is "immutable" — you can't call it Scrum if you pick and choose. This stance echoes the first-edition XP position of kent-beck in xp-explained-first-edition and reflects the concern that selective adoption leads to dark-agile — the appearance of Agile without the substance.
Significance
The Scrum Guide is unusual in the software methodology world: a freely available, CC-licensed, actively maintained specification document for a widely used framework. Its updates have been closely watched and debated by the Scrum community. The 2020 update, in particular, was seen as an attempt by ken-schwaber and jeff-sutherland to course-correct against the agile-industrial-complex — the certification and consulting industry that had grown up around Scrum, often teaching practices inconsistent with the Guide.
The Guide is available free at scrumguides.org.