Glossary
What does a scrum master do?
The scrum master owns the process and removes impediments — not the assignment of work. Responsibilities and the most common misplacement.
The scrum master is responsible for the process working and the team being able to get on with it. They are neither a manager nor a project lead — probably the most common misplacement in the whole framework.
The responsibilities
Removing impediments the team cannot remove itself; keeping the events — planning, the daily, review, retrospective — useful rather than ritual; and shielding the team from interruptions that reach into the middle of a sprint.
What is not included
Assigning work, chasing progress or appraising performance. The moment that happens, people stop naming problems in the retrospective — and the only built-in improvement mechanism stops working.
Does it need to be full time?
For one team, rarely. It is common for somebody on the team to carry the role alongside their work. It only becomes a problem when that same person also appraises how well people perform, because then the precondition for candid retrospectives is gone.
FAQ
Is the scrum master the team's boss?
No. They have no authority over the work. They are responsible for the process, not the people.
Can someone on the team take the role?
Yes, and on small teams that is normal. It only becomes a problem if the same person also does performance reviews.
Does Kanban need a scrum master?
Not as a role. The job — removing impediments and improving the process — still exists and somebody has to do it.