Fingernails can serve as indicators of overall health, with changes in their appearance potentially signaling underlying medical conditions. For instance, brittle or splitting nails may result from repeated wetting and drying, leading to onychoschizia. Spoon-shaped nails, or koilonychia, are often linked to iron deficiency anemia and may also be associated with skin diseases like psoriasis or thyroid disorders. Yellow discoloration can indicate fungal infections or reactions to products such as nail polish, and in rare cases, may signal more serious issues like diabetes or respiratory diseases. Dark streaks under the nail could be a sign of melanoma, a serious form of skin cancer. Regular monitoring of nail health and consulting healthcare professionals when significant changes occur are essential for early detection and management of potential health issues.