Nail infections, or onychomycosis, are fungal, bacterial, or viral infections affecting the fingernails or toenails. They often cause discoloration, thickening, brittleness, and deformity. Fungal infections are the most common, typically caused by dermatophytes, yeasts, or molds, and thrive in warm, moist environments. Risk factors include poor hygiene, diabetes, immunosuppression, and frequent nail trauma. Diagnosis involves clinical examination, microscopy, and culture. Treatment options range from topical and oral antifungals to surgical debridement, depending on severity. Proper foot and hand hygiene, along with early intervention, help prevent and manage infections effectively.