Simply expressed, velocity is the amount of work that a team can get done in a fixed timeframe. It indicates the average amount of Product Increment created during a Sprint by a Scrum Team. A Sprint Burn-down Chart is a helpful tool is used by the Scrum Team to maintain and share information about the team’s velocity. While a Team's velocity will vary each sprint, over time, a well-functioning Scrum Team's velocity should steadily trend upward each Sprint. With the knowledge of team velocity, a Product Owner can project on how many sprints are required for the team to deliver the desired level of functionality that can be released. Since different teams may have different approaches to estimation, we should avoid comparing velocity between teams.