Hormones are chemical messengers produced by endocrine glands that travel through the bloodstream to regulate various bodily processes, including growth, metabolism, mood, immune function, and reproduction. They work by binding to specific receptors on target cells, triggering responses that maintain balance and support essential functions. Key hormones include insulin for blood sugar regulation, growth hormone for development, cortisol for stress response, and reproductive hormones like estrogen and testosterone. Hormonal imbalances can lead to health issues, highlighting their critical role in maintaining overall well-being.