Sprint
A timeboxed period of one month or less during which the Scrum Team turns Product Backlog items into a Done Increment.
What it means
The Sprint is the heartbeat of Scrum: a container for all other events. It has a fixed length agreed on by the team, typically one to four weeks, and does not change during the Sprint even if the amount of work does.
During the Sprint, quality goals do not decrease, scope may be clarified and renegotiated with the Product Owner as more is learned, and the Sprint Goal stays stable. A new Sprint starts immediately after the previous one ends.
Common mistakes
A Sprint can be cancelled only by the Product Owner, and only if the Sprint Goal becomes obsolete, which is rare in practice. Shorter Sprints reduce risk and produce more frequent feedback but add coordination overhead for planning and review.
Example
A team runs two-week Sprints starting every other Monday, always closing with a Sprint Review on the last Friday afternoon.