Sprints are fixed length periods of work that last one month or less to create consistency and ensure short iterations for feedback in order to inspect and adapt both how work is done and what is being worked on. If cycles are longer, then the spirit of frequent feedback cycles can be lost. Longer Sprint may also get too complex and may increase risk. A new Sprint starts immediately after the conclusion of the previous Sprint.| Scrum.org
The Scrum Master is accountable for establishing Scrum. They do this by helping everyone understand Scrum theory and practice, both within the Scrum Team and the organization while serving the Scrum Team as well as the larger organization.| Scrum.org
The ultimate place to learn more about Scrum from the organization that created it. These resources include videos, papers, guides and much more.| Scrum.org