Velocity is the measured output of a Scrum team: the average number of story points completed across recent sprints. It is used as an input to release planning — if a team has velocity 30 and the remaining backlog is estimated at 300 points, roughly 10 sprints remain. Velocity is a forecasting tool, not a performance target; using it to pressure teams inflates estimates and destroys its predictive value (Keith 2021, see source-agile-game-development).
Velocity is team-specific and story-point scales are not comparable across teams.
Related: sprints, user-stories, scrum-in-game-development, product-backlog