Scrum Master (aka team facilitator, coach or change agent) is a role in the Scrum Methodology. Sometimes it is written as “ScrumMaster” although, that spelling is no longer popular. Either spelling is correct and commonly used. The reason for the spelling is related to naming conventions in software development and the original Wiki. The Scrum Master is responsible for the health of the team. Scrum Mastery is a concept and role found in any good description of Scrum Guide and is a part of the terminology used. They are sometimes referred to as the coach or change agent but, this title is usually not appropriate.
Scrum Masters are not neutral and objective, nor should they be. After all, they are accountable for helping everyone understand Scrum theory, practices, rules, and values, so they should have some opinions about those things – and be able to persuade others to adopt them. In many cases, they facilitate a Team with specific goals in mind; they are ‘leaders who facilitate’, not ‘neutral facilitators’. They are guides, coaches, mentors, trainers, and (ultimately) facilitators.
As a change agent they are in service to both the organization and the team by helping with a focus on impediment mitigation or abatement. A good Scrum Master is someone who likes to work with people and can establish a pattern of continuous improvement.
The role of Scrum Master is distinctly and purposefully separated from that of the Product Owner so that there is a balance in both a a separation of interest and concerns.
A ScrumMaster with technical background is not required but, can help. However, the ScrumMaster does need to be passionate about people.
For more reading
Read Certified Scrum Master and how this key industry certification fueled an industry.
Read Scrum FAQ for a better understanding of Scrum.