Hypothyroidism is the most common type of thyroid disorder. It means your thyroid gland is not active enough. This tiny gland is found in the front of your neck. Its job is to make thyroid hormone. If the gland is underactive, it may not make enough thyroid hormone. Thyroid hormones control how your body uses energy. They affect almost every organ in your body. When your thyroid doesn’t make enough of these hormones, parts of your body slow down.