Use this tag for questions about the velocity metric or velocity tracking within an agile context.
Velocity is a trailing metric that tracks work completed over an historical window, such as a series of Scrum Sprints or other agile iterations. A stable team velocity also allows for reasonable forecasts of lead and cycle times within a project.
Velocity can be used as a detective control for hidden blockers or process impediments, and as a baseline capacity-planning value during Sprint Planning. The latter is generally most effective when considered as a statistical range, or as a sustainable upper bound of team capacity that functions as a sanity check to ensure that too much work hasn't been pulled into an agile iteration or release plan.
Velocity is not a performance, efficiency, or productivity metric. It should never be used as a management target, or in a misguided attempt to "hold people accountable."