Every Scrum team has three roles: product owner, ScrumMaster, and development team. The individuals in these roles work together to bring a product from an idea to life.

Product Owner

The product owner is the member of the Scrum team charged with maximizing the value of the team’s work. The product owner holds the product vision and works closely with stakeholders, such as end users, customers, and the business to cultivate and nurture a community around the product. They facilitate communication between the team and the stakeholders and ensure the team is building the right product. They describe what should be built and why, but not how.

To fulfill the role, the product owner:

1. Decides what goes into the product backlog and, equally important, what does not
2. Maintains the product backlog and orders the items in the backlog to deliver the highest value
3. Works with the team and the stakeholders to continuously improve the quality of the product backlog and everyone’s understanding of the items it contains
4. Decides which product backlog items to ask the team deliver in the current sprint
5. Decides when to ship the product, with a preference toward more frequent delivery.
6. The product owner may be supported by other individuals but must be a single person to maintain clarity of the vision and priorities.

ScrumMaster

The ScrumMaster is a servant leader, helping the rest of the Scrum team progress. The ScrumMaster keeps the Scrum team productive and learning. They must have a good understanding of the Scrum framework and the ability to train others to use it. The ScrumMaster has three core responsibilities:

Coach the team

The ScrumMaster helps the entire team perform better. They help the product owner understand how to create and maintain the product backlog so the project is well defined and work flows smoothly to the team. They also work with the whole Scrum team to determine the definition of done. The ScrumMaster coaches the team on how to execute the Scrum process, helping them learn and use the framework and find and implement technical practices so they can reach done at the end of each sprint.

Keep the team moving forward

As a servant leader, the ScrumMaster fosters the team’s self-organization and then sees that distractions and impediments, or roadblocks, to the team’s progress are removed. Impediments may be external to the team, like lack of support from another team, or they could be internal, like the product owner not knowing how to prepare a proper product backlog. They may also facilitate regular team meetings to ensure that the team progresses on its path to done.

Help everyone understand Scrum

The ScrumMaster ensures that Scrum is understood and in place, both inside and outside the team. They help people outside the team understand the process, as well as which interactions with the team are helpful and which are not. The ScrumMaster helps everyone improve to make the Scrum team more productive and valuable.

Development team member

The development team does the actual work of delivering the product increment. The team is a cross-functional group of professionals who, among them, have all the necessary skills to deliver each increment of the product. All team members should be available to the team and the project full time.

The product owner makes an ordered list of what needs to be done. The development team members then forecast how much they can do in one sprint and self-organize to get the work done, deciding among themselves who does what to produce the new product increment. - See more at: https://www.scrumalliance.org/why-scrum/core-scrum-values-roles#sthash.oB2Kpf8C.dpuf