Scrum relies on a self-organizing, cross-functional team. The scrum team is self-organizing in that there is no overall team leader who decides which person will do which task or how a problem will be solved. Those are issues that are decided by the team as a whole. The team is cross-functional so that everyone necessary to take a feature from idea to implementation is involved.
These agile development teams are supported by two specific individuals: a scrum master and a product owner.
Scrum projects make progress in a series of sprints, which are timeboxed iterations no more than a month long.
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