A movable book is one that changes form upon action by the reader. The category of movable books includes pop-ups, pull tabs, lift-the-flaps, revolving wheels and other three-dimensional devices which spring to life upon the opening of a page. Movable books were perhaps the first form of interactive media and today they provide a welcome opportunity to engage one's hands, eyes, brain and imagination in a culture where much of our entertainment takes place via remote control.

Artists who construct pop-ups and other movable elements are called paper engineers. The magic they perform is the result of many hours of trial and error. The scientific principle underlying the building of a pop-up is that of kinetic energy, or the energy created by movement. Whether simple or elaborate in design, pop-ups surprise and delight both children and adults.

The first movable books appeared in the 15th and 16th centuries and were actually used for astronomical, scientific and medical purposes. It was not until the middle of the 19th century that movable books became widely available and were subsequently targeted to appeal to children.