A spear is a pole weapon consisting of a shaft, usually of wood, with a pointed head. The head may be simply the sharpened end of the shaft itself, as is the case with bamboo spears, or it may be made of a more durable material fastened to the shaft, such as flint, obsidian, iron, steel or bronze. The most common design for hunting or combat spears since ancient times has incorporated a metal spearhead shaped like a triangle, lozenge or leaf. The heads of fishing spears usually feature barbs or serrated edges. Spears can be divided into two broad categories: those designed for thrusting in melee combat and those designed for throwing (usually referred to as javelins). The spear has been used throughout human history both as a hunting and fishing tool and as a weapon. As a weapon, it may wielded with either one hand or two. It was used in virtually every conflict up until the modern era and was most likely the most commonly used weapon.