The age at which boys stop growing taller is usually around 18-20 years old and is related to whether the epiphysis is closed or not. During adolescence, the long bones consist of a backbone, two epiphyses and epiphyseal cartilage, which is located between the backbone and epiphyses. The growth hormone is secreted by the pituitary gland, and the epiphyseal cartilage grows when stimulated by the hormone, which results in the growth of cartilage and the formation of bone on both sides. As the epiphyseal cartilage grows, it gradually becomes thinner and finally all the cartilage ossifies and stops developing, usually around 18-20 years old for boys and relatively earlier for girls. The epiphyseal cartilage remains between the diaphysis and the epiphysis, i.e., the epiphyseal line. If the epiphysis is not closed, it means that the height will continue to grow, but if it is closed, it proves that the growth has stopped.