Our hair is formed by groups of hair roots containing 1-5 roots. These groups are referred to as follicular units. In a person with healthy hair, the hair roots located in the front are usually in groups of one or two. Groups of three are seen towards the back, whereas on the nape hair root groups of three, four and five are more commonly found. In hair losses occurring in the front area, we lose the follicular units containing single and double roots. As hair loss progresses towards the back, we lose hair root groups of two and three. For a hair transplant that looks natural, it is necessary to plant them like the distribution of lost hair. For this reason, the grafts (transplanted tissue fragments containing hair roots) must not contain three, four or five hair roots, but one or two and, to a lesser extent, three roots.