Even if you are new to Scrum, you may have heard of a role called the ScrumMaster. The ScrumMaster is the team's coach, and helps Scrum practitioners achieve their highest level of performance.
In the Scrum process, a ScrumMaster differs from a traditional project manager in many ways, including that this role does not provide day-to-day direction to the team and does not assign tasks to individuals.
A good ScrumMaster shelters the team from outside distractions, allowing team members to focus maniacally during the sprint on the goal they have selected.
While the ScrumMaster focuses on helping the team be the best that it can be, the product owner works to direct the team to the right goal. The product owner does this by creating a compelling vision of the product, and then conveying that vision to the team through the product backlog.
The product owner is responsible for prioritizing the backlog during Scrum development, to ensure it’s up to par as more is learned about the system being built, its users, the team and so on.
The third and final role in Scrum project management is the Scrum team itself. Although individuals may join the team with various job titles, in Scrum, those titles are insignificant. Scrum methodology states that each person contributes in whatever way they can to complete the work of each sprint.
This does not mean that a tester will be expected to re-architect the system; individuals will spend most (and sometimes all) of their time working in whatever discipline they worked before adopting the agile Scrum model. But with Scrum, individuals are expected to work beyond their preferred disciplines whenever doing so would be for the good of the team.
One way to think of the interlocking nature of these three roles in this agile methodology is as a racecar.
The Scrum team is the car itself, ready to speed along in whatever direction it is pointed. The product owner is the driver, making sure that the car is always going in the right direction. And the ScrumMaster is the chief mechanic, keeping the car well tuned and performing at its best.