This section serves as a very light introduction to the three roles in Scrum: Scrum team, Product owner, and ScrumMaster . While the book focuses predominantly on the ScrumMaster role, we will touch upon the other roles in more detail due to the natural interconnectedness of all three. As you probably already know, people get very anxious about roles and responsibilities; we'll go into more detail about Scrum (and non-Scrum) roles in Chapter 9, Shaping the Agile Organization.
The Scrum team includes the product owner, ScrumMaster, and the team members, whereas the Scrum delivery team is a subset made up of only the technical team members. The entire Scrum team huddles around a problem (a requirement from an ordered list known as the Product Backlog) and innovates solutions. Scrum teams should be five to nine team members, dedicated to the life of the project (and perhaps beyond), cross-functional, empowered, and self-organizing. Scrum teams plan, estimate, and commit to their work, rather than a manager performing these functions for them. The end goal of the team is to deliver a potentially shippable product increment that meets an agreed-upon Definition of Done each and every sprint. The George Cleverly shoe craftsmen would be considered Scrum delivery team members while the craftsmen, customer, and shoe design consultant together would comprise the overall Scrum team (it takes everyone's participation to make the right shoe).
The product owner is responsible for the product's success. In other words, while the team is responsible for delivering a quality solution, the product owner is responsible for knowing his market and user needs well enough to guide the team toward a marketable release sprint after sprint. There are different types of product owners in different types of projects, but regardless of the technical situation or the desired outcome, there should be one (and only one) product owner who makes final decisions about the direction of the product and the order in which features should be developed. The product backlog, or list of items to be completed by the Scrum team, is ordered by the product owner so as to reflect his most valuable requests or changes for the product in development. The product owner, since he is representing the "what" and "why" of the system, should be available to the team to have regular dialogs about the requirements in the product backlog; additionally, the product owner must make the product vision clear to everyone on the team and regularly maintain the product backlog in keeping with the product vision. The product owner always keeps the next set of product backlog items in a ready state so that the team always has work in the queue for the next sprint. The George Cleverley shoe customer is the 'purest' product owner a team can get—the actual person paying for the product!
The ScrumMaster safeguards the process. He/she understands the reasons behind and for an empirical process, and does his or her best to keep product development flowing as smoothly as possible. This "servant leader" (take a look at Servant Leadership, by Robert K. Greenleaf, Paulist PR) protects team members from interruptions in order to keep them focused on their sprint commitments, as well as helps the product owner get the product backlog in order if he or she does not understand how to do so. Additionally, ScrumMasters facilitate all Scrum meetings, ensuring that everyone on the team understands the goals and that they share a commitment together as a true team and not just as a collection of individuals. ScrumMasters remove obstacles that prevent a steady flow of high-value features; many times, the obstacles are organizational in nature.
Think of the ScrumMaster as the Switzerland of the Scrum process—remaining neutral, helping both business stakeholders and development, interacting at the right times to create the most important and most valuable features first.