Nail ridging looks like thin lines running vertical with the nail plate from cuticle to free edge. Ridging occurs naturally as we age and can be a symptom of a dried out nail plate. The nail plate rides forward on the nail bed upon a series of rails and grroves much like a train rides forward on its tracks. The rails are on the surface of the nail bed and the grooves are on the underside of the nail plate. When the nail plate becomes dried out, these raisl and grooves become apparent on the nail plate as ridging. Please see my web page on Nail Disorders @ www.hooked-on-nails.com (link approved by Moderator 1) for a picture of nail ridging.