A Balisong, otherwise known as a butterfly knife or fan knife, is a folding pocket knife with two handles counter-rotating around the tang such that, when closed, the blade is concealed within grooves in the handles. It is sometimes called a Batangas knife. In the hands of a trained user, the knife blade can be brought to bear quickly using one hand. Manipulations, called "flipping" or "fanning", are performed for art or amusement.
The Balisong is commonly used by Filipino people as a pocket utility knife. It is so popular in the Philippines that an urban legend exists about every Batangueño carries it everywhere he or she goes. Hollowground balisongs were also used as straight razors before conventional razors were available in the Philippines.