This is a good question, and gets asked a lot and the terms are often confused and misused. Generally a flyer or a leaflet is a 1 page single sheet that is printed 1 or 2 sided. A brochure is a sheet that is folded, whether it be in half or in thirds or multiple folds. And then there are booklets, these are a bound book of multiple pages which have multiple sheets stapled or bound together to form a book or booklet.