Hormones are chemical messengers that are produced by glands in the endocrine system, including the pituitary, thyroid, and adrenal glands, and the pancreas. Each hormone has a specific target organ or tissue, where it binds to receptors and triggers a response. Hormones can affect a wide range of physiological and behavioral processes, including growth and development, metabolism, reproductive function, stress response, and mood. Imbalances in hormone levels can lead to a variety of health issues, including thyroid disorders, diabetes, and infertility.