The thyroid is a small, butterfly-shaped gland in the neck that produces hormones regulating metabolism, growth, heart rate, and energy. When it becomes underactive, overactive, or develops nodules or enlargement, it may cause fatigue, weight changes, swelling, or hormonal imbalance. Early diagnosis is vital to prevent complications. Doctors usually assess thyroid function through blood tests (TSH, T3, T4), imaging like ultrasound or thyroid scans, and in some cases a fine needle aspiration biopsy for nodules. With timely detection and treatment, thyroid disorders can be managed effectively, ensuring balanced hormone levels and better long-term health.