ABSTRACT
In this part of "The Nails -A Review", the anatomy of the nail is demonstrated. Some nails affection is discussed. To start with, we covered in short, some main topics as abnormal nail discoloration which included most leukonychial nail affections and some causes of melanonychia, subungual melanoma, yellow nail syndrome and nail discoloration from drugs as well as some rare congenital causes of nail discoloration. Hereditary diseases involving the nails especially those associated with atrophic changes, total and partial absence of nails, hypertrophic congenital nail changes and periungual involvement were briefly discussed. We tried to illustrate these conditions by available photographs. This could help as a quick short reference to these nails changes. To start with, it is important to know clearly the anatomy of the nail unit in order to understand the nail affection in disease