Scrum Roles

In scrum principle, there are three roles: The Product Owner, The Team, and The Scrum Master.
Together these are known as The Scrum Team.

All other member, e.g: Project Manager,  Delivery Manager, Solution designer, System Administrator, all are part of team or external resource.

Let's discussed in details:

Product Owner: Product owner is most demanding person, and all responsible for maximizing return on investment (ROI) by identifying product features, translating these into a prioritized list, deciding which should be at the top of the list for the next Sprint, and continually re-prioritizing and refining the list. He has profit and loss responsibility for the product, assuming it is a commercial product – the highest-business-value lowest-cost items. In practice, ‘value’ is a fuzzy term and prioritization may be influenced by the desire to satisfy key customers, alignment with strategic objectives, attacking risks, improving, and other factors. 

In few cases, the Product Owner and the customer are the same person; this is common for internal applications. In others, the customer might be millions of people with a variety of needs, in which case the Product Owner role is similar to the Product Manager or Product Marketing Manager position in many product organizations. It is important to note that in Scrum there is one and only one person who serves as – and has the final authority of – Product Owner, and he or she is responsible for the value of the work.

Team: The team builds the product that the Product Owner indicates: the application or website,

for example. The Team in Scrum is “cross-functional” – it includes all the expertise necessary

to deliver the potentially shippable product each Sprint – and it is “self-organizing” (self-managing),

with a very high degree of autonomy and accountability.

The Team in Scrum is seven plus or minus two people, and for a software product the Team might include people with skills in analysis, development, testing, interface design, database design, architecture, documentation, and so on. The Team develops the product and provides ideas to the Product Owner about how to make the product great. In Scrum the Teams are most productive and effective if all members are 100 percent dedicated to the work for one product during the Sprint; avoid multitasking across multiple products or projects. Stable teams are associated with higher productivity, so avoid changing Team members. Application groups with many people are organized into multiple Scrum Teams, each focused on different features for the product, with close coordination of their efforts. Since one team often does all the work (planning, analysis, programming, and testing) for a complete customer-centric feature, Teams are also known as feature teams.

Scrum Master: The Scrum Master helps the product group learn and apply Scrum to achieve business value. The Scrum Master is not the manager of the Team or a project manager; instead, the

Scrum Master serves the Team, protects them from outside interference, and educates and guides the Product Owner and the Team in the skillful use of Scrum. The Scrum Master makes sure everyone (including the Product Owner, and those in management) understands and follows the practices of Scrum, and they help lead the organization through the often difficult change required to achieve success with agile development. Since Scrum makes visible many impediments and threats to the Team’s and Product Owner’s effectiveness, it is important to have an engaged Scrum Master working energetically to help resolve those issues, or the Team or Product Owner will find it difficult to succeed. There should be a dedicated full-time Scrum Master, although a smaller Team might have a team member play this role (carrying a lighter load of regular work when they do so). Great Scrum Masters can come from any background or discipline: Engineering, Design, Testing, Product Management, Project Management, or Quality Management.

Note: Scrum Master and the Product Owner cannot be the same individual, there is no role of project manager in Scrum.

Scrum Master does not tell people what to do or assign tasks – they facilitate the process, supporting the Team as it organizes and manages itself. If the Scrum Master was previously in a position managing the Team, they will need to significantly change their mindset and style of interaction for the Team to be successful with Scrum.

Depend on team size, location. Group Scrum Master will there for big team, generally called scrum of scrum.

Last Words!
Thanks! Please like and share you input if any. Happy learning and implementation.

Ref: Scrum books and URL's.