✔ 最佳答案
An uncircumcised penis has a foreskin. A circumcised penis' foreskin has been cut off by surgery (circumcision). The following link has an illustration, and it's from a government health site:
http://www.nlm.nih.gov/medlineplus/ency/imagepages/19093.htm
The foreskin's purpose is to protect the head of the penis. It keeps it moist, so it doesn't end up drying up like your hands can, so no cracks develop on the head. It's also supposed to keep it sensitive (see the medical study in the Fox News link below). It also slides up and down during sex and masturbation (which feels good since its already lubricated). So it doesn't just create unsanitary conditions; all it takes is a simple 5 second rinse when you shower. In general, this link does a good job at describing the function of the foreskin. This website describes the difference in words:
http://www.cirp.org/pages/anat/
The USA is the last developed nation doing it without medical or religious reasons, but even our rates have fallen to as low as 14% in some states, opposed to about 90% nationally in the 60s and 70s.