The Scrum Framework organizes people by defining three distinct sets of responsibilities. Each set of responsibilities is called a role, and individuals play different roles when they participate in Scrum teams.
It is important to realize that these roles do not necessarily correspond to actual individuals. It is quite possible for people to play more than one role. It is not uncommon, for instance, for a developer also to play the role of Scrum Master (provided they have the necessary skills and experience to do so). Roles are sets of responsibilities; ...