Foreskin: The natural loose skin that covers the glans. On an uncircumcised man there is sufficient loose skin to enclose the glans in a tube, at least when the penis is flaccid. When erect, on some uncircumcised men, the foreskin retracts off the glans. On others, it stays over the glans. Some men have very tight foreskins, a condition called phimosis, in which the glans can never be totally uncovered. In many young boys, phimosis is normal, and as they reach puberty, the condition goes away.
Circumcision removes most of the foreskin. What’s left varies with each man, some still have enough to pull over the glans, while others are circumcised very ‘tight,’ leaving only a slightly flexible covering over the shaft of the penis.
There’s no way to tell, but many people believe a circumcised man has less feeling in his penis. Your author is circumcised, and still has plenty of wonderful feeling available, although sometimes he wonders if there could have been even more.
Some men who can pull their foreskins entirely over their glans enjoy playing with pinching the end of the foreskin closed, and then filling it with urine, holding it for a while, and then letting it go in a big splash.
See also: Circumcision.