The thyroid gland is a small, butterfly-shaped organ located in the front of the neck, just below the Adam's apple. It plays a crucial role in regulating the body's metabolism by producing hormones that control how the body uses energy. These hormones influence various functions, including heart rate, body temperature, and weight. When the thyroid gland is not functioning properly, it can lead to health issues. An underactive thyroid, known as hypothyroidism, can cause fatigue and weight gain, while an overactive thyroid, or hyperthyroidism, may result in weight loss and increased heart rate. Regular check-ups can help monitor its health.