Crescents on the nails are not necessarily related to health. Crescent is the nail metabolism process appeared in the process of incomplete keratinization of the nail, also belongs to the distal region of the nail mother. Nails are in constant metabolism, nails in the growth process, the two sides of the growth rate is fast, the middle of the growth rate is slow, gradually in the middle of the nails to form a crescent shape, with the complete keratinization of the nails, the crescent also gradually disappear. The fact that some people do not have a crescent does not mean that the patient is in poor health. These people may have slow nail growth, or the nail matrix is positioned downward, and the crescent visible to our naked eye is small or invisible.