How old should a child be for the foreskin to be retracted?

Patient's question:

Six-year-old child, unable to retract the foreskin, very small foreskin opening

Doctor's answer:

The foreskin refers to the double-layered skin of the penis that folds over the glans. In infancy, the foreskin is often longer, covering the glans and the external urethral orifice, which are not visible. This is known as physiological phimosis. As one grows older, the penis and foreskin gradually develop. During puberty, the foreskin retracts backward, and by adulthood, the glans becomes exposed.