What is a page shelf in Tableau?

The Pages shelf divides a view into a sequence of pages — one per member of the field you place on it — displaying one at a time against a fixed axis.

It adds a control with forward and back buttons, an automatic play at adjustable speed, and an option to show a trail of previous positions.

Because the axis does not move between pages, it is a good way to show change over time: a scatter plot animated by month makes movement obvious in a way a static chart does not.

Its limitation is that the control does not carry through to Server, so it belongs in exploration and live presentation rather than in a published dashboard.