Spirit possession constitutes an important element of Vodou, being at the heart of many of its rituals. The person being possessed is referred to as the "chwal" or "chual" (horse); the act of possession is called "mounting a horse". Vodou teaches that a lwa can possess an individual regardless of gender; both male and female lwa can possess either men or women. Although children are often present at these ceremonies, they are rarely possessed as it is considered too dangerous. While the specific drums and songs used are designed to encourage a specific lwa to possess someone, sometimes an unexpected lwa appears and takes possession instead. In some instances a succession of lwa possess the same individual, one after the other.