The nails can provide important clues about overall skin and systemic health. Nail disorders may result from infection, inflammation, trauma, aging, nutritional deficiencies, or underlying medical conditions. Common symptoms include discoloration, thickening, brittleness, lifting of the nail plate, or changes in nail shape. One of the most common nail diseases is onychomycosis, a fungal infection of the nail plate and surrounding structures. Other nail conditions include bacterial infections, chronic paronychia, psoriasis, trauma-related nail damage, inflammatory nail disorders, and changes associated with vitamin or mineral deficiencies such as iron, zinc, or biotin deficiency.