Velocity - The good and the bad of it

"Velocity is an indication of the average amount of Product Backlog turned into an Increment of product during a Sprint by a Scrum Team, tracked by the Development Team for use within the Scrum Team. There is no such thing as a Good Velocity or a Bad Velocity. Remember, it is based on relative estimations. Let’s understand with some examples on how a powerful Velocity metric can turn from Good, to Bad, to Ugly."