The Scrum Master is responsible for promoting and supporting Scrum. Scrum Masters do this by helping everyone understand Scrum theory, practices, rules, and values.
Scrum Master is not a new name for the traditional (Project) Manager. Rather, the Scrum Master is a true leader who leads through serving.
The Scrum Master Educates, Coaches, Mentors and Facilitates to higher performance and agility.
The Scrum Master serves the Developers, the Product Owner and the Organization.
Also see: Scrum Masterr as a Coach, Scrum Master as a Leader