Original: It may consist of a single sheet of paper that is printed on both sides and folded in half, in thirds, or in fourths (called a leaflet), or it may consist of a few pages that are folded in half and stapled at the crease to make a simple book.
Simplified: It can be made up of a single sheet of paper that is printed on both sides and folded in half, in thirds, or in fourths (called a leaflet).