What is Pages shelf?

The Pages shelf breaks a view into a series of pages, one per member of the field placed on it, and shows one at a time on a fixed axis.

It provides a playback control — forward, back, and automatic play at a chosen speed — along with an option to show a trail of previous positions.

Because the axis stays constant across pages, movement is directly comparable, which makes it a good way to show change over time in a scatter plot or map.

The catch is that the control does not survive publishing to Server, so it belongs in analysis and presentation rather than in a dashboard other people will use.