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 serves the Developers, the Product Owner and the Organization through Educating, Facilitating and Coaching them to higher performance and agility.