The thyroid is a butterfly-shaped gland located in the neck. Thyroid hormones play a vital role in regulating many body functions.The thyroid is a butterfly-shaped gland located in the neck. Thyroid hormones play a vital role in regulating many body functions. If you have thyroid disease, you can experience a variety of symptoms. Common symptoms of thyroid problems include feeling tired, unexplained weight gain, feeling sensitive to colds, depressed mood etc.