Hypothyroidism and hyperthyroidism are two distinct thyroid disorders with opposite effects on the body. Hypothyroidism results from an underactive thyroid gland, leading to insufficient production of thyroid hormones. Symptoms include fatigue, weight gain, cold intolerance, and depression. In contrast, hyperthyroidism arises from an overactive thyroid gland, causing excessive thyroid hormone release. This condition presents with symptoms like weight loss, anxiety, rapid heartbeat, and heat intolerance. Hypothyroidism is commonly caused by Hashimoto’s disease or iodine deficiency, while hyperthyroidism is often linked to Graves’ disease or nodules. Diagnosis involves blood tests, and treatment aims to restore hormone balance through medication, radioactive iodine, or surgery, depending on the disorder’s severity.