The process whose specific outcome is the progression of a nail over time, from its formation to the mature structure. A nail is a horn-like envelope covering the outer end of a finger or toe, and consists of the nail plate, the nail matrix and the nail bed below it, and the grooves surrounding it. [ http://openisbn.com/search.php?q=0323025781&isbn=1/ GOC:bf http://purl.obolibrary.org/obo/UBERON_0001705 http://en.wikipedia.org/wiki/Nail_(anatomy) ]