Pop-up book

A pop-up book is any book with three-dimensional pages, often with elements that pop up as a page is turned. The terminology serves as an umbrella term for movable book, pop-ups, tunnel books, transformations, volvelles, flaps, pull-tabs, pop-outs, pull-downs, and other features each performing in a different manner. Three-dimensional greeting cards use the same principles. Design and creation of such books in arts is sometimes called "paper engineering". This usage should not be confused with traditional paper engineering, the engineering of systems to mass-produce paper products.

Animated books combine three elements: story, colored illustrations which include text, and "two or more animated illustrations with their movement mechanisms working between a doubled page". In 1938, Julian Wehr's animations for children's books were patented as "moving illustrations" that move the picture up and down and horizontally at the same time with a single movement.

Transformations show a scene made up of vertical slats. When a reader pulls a tab on the side, the slats slide under and over one another to "transform" into a totally different scene. Ernest Nister, one of the early English children's book authors, often produced books solely of transformations. Many of these have been reproduced by the Metropolitan Museum of Art.^{[citation needed]}

Tunnel books (also called peepshow books) consist of a set of pages bound with two folded concertina strips on each side and viewed through a hole in the cover. Openings in each page allow the viewer to see through the entire book to the back, and images on each page work together to create a dimensional scene inside. This type of book dates from the mid-18th century and was inspired by theatrical stage sets. Traditionally, these books were often created to commemorate special events or sold as souvenirs of tourist attractions. The term "tunnel book" derives from the fact that many of these books were made to commemorate the building of the tunnel under the Thames River in London in the mid-19th century. In the United States, tunnel books were made for such attractions as World's Fairs and the New York Botanical Gardens.

Recently the tunnel book format has been resurrected by book artist Carol Barton and others as a sculptural book form. Artists are interested not only in the book's interior views, but also in treating the side accordions and covers as informational and visual surfaces. A selection of tunnel books by Carol Barton is archived in the special collections of Virginia Commonwealth University's James Branch Cabell Library.

Volvelles are paper constructions with rotating parts. An early example is the Astronomicum Caesareum, by Petrus Apianus, which was made for the Holy Roman Emperor Charles in 1540. The book is full of nested circular pieces revolving on grommets.

About 1765, English printer Robert Sayer began experimenting with a novelty format for the juvenile book market, an early forerunner to interactive movable books, according to book historian Peter Haining. The outcome was the creation of the "metamorphoses" format, "a thin book of four sections each with two flaps which folded over, and on each section an interchangeable picture. Beneath those pictures appeared some descriptive lines of verse, and as the reader turned up the flaps in the correct order in the text difference scenes were revealed".

Sayer created books featuring the "Harlequins" from popular theater pantomimes. The black and white publications, which were also called Harlequinades or turn-up books, sold for sixpence and the hand-colored ones for one shilling.