From The Art and Popular Culture Encyclopedia
An altered book artist takes a book (old, new, recycled or multiple) and cuts, tears, glues, burns, folds, paints, adds to, collages, rebinds, gold-leafs, creates pop-ups, rubber-stamps, drills, bolts, and/or be-ribbons it. The artist may add pockets and niches to hold tags, rocks, ephemera, or other three-dimensional objects. Some change the shape of the book, or use multiple books in the creation of the finished piece of art.
Altered books may be as simple as adding a drawing or text to a page, or as complex as creating an intricate book sculpture.