Hormonal changes refer to fluctuations in levels of hormones within the body. Hormones are chemical messengers produced by glands that regulate various bodily functions, including mood, emotions, growth, reproduction, and metabolism.
The endocrine system is a network of glands throughout the body that produce hormones. It includes glands such as the pituitary gland (master gland), thyroid gland (regulates metabolism), adrenal glands (release stress hormone cortisol), etc.
Puberty is a period during adolescence when hormonal changes lead to physical development such as secondary sexual characteristics (like breast development or facial hair) along with emotional changes.