Hormones are chemical substances that are synthesized and produced by specialized glands to control and regulate the activity of certain cells and organs.
The glands which produce hormones are known as endocrine glands.
The hormone secreted by the thyroid gland is thyroxine(thyroid hormone).
Thyroid gland:
The thyroid gland is a ductless endocrine gland situated in the anterior/front portion of the neck.
It roughly resembles the shape of a butterfly.
It is also one of the largest endocrine glands.
Thyroxine:
It is a hormone that is made by the thyroid gland and contains iodine.
Thyroxine increases the rate of chemical reactions in cells and helps control growth and development.