Hair growth occurs from hair follicles in the scalp, where living cells multiply and produce hair strands made mostly of keratin, a hard protein. Hair grows in a cycle with phases called anagen (growth), catagen (transition), and telogen (rest). Growth is fueled by nutrients and oxygen supplied by blood vessels to the follicle. Proper nutrition—especially protein, iron, omega-3 fatty acids, vitamins (such as A, B7 biotin, C, and D), zinc, and selenium—plays a crucial role in promoting healthy hair growth and maintaining hair follicle health. External factors like scalp care, avoiding excessive heat or trauma, and using growth-promoting products like caffeine-based shampoos can also support hair growth. Hair grows about 1 cm per month during the anagen phase, which can last several years depending on genetics. In summary, hair growth is driven by living follicles that produce keratin strands, nourished by blood supply and essential nutrients, and can be supported by healthy nutrition and proper scalp care.