Passage: A burn down chart is a graphical representation of work left to do versus time. The outstanding work (or backlog) is often on the vertical axis, with time along the horizontal. That is, it is a run chart of outstanding work. It is useful for predicting when all of the work will be completed.  It is often used in agile software development methodologies such as Scrum.  However, burn down charts can be applied to any project containing measurable progress over time.

Question: Where is the backlog normally kept?
vertical axis