- personal websites where the model does not get naked, or at least does not show pussy or [[tits].
Non-nude originally was the home of many underage models, who would (for money, of course) flash their butt, show off in small bathing suits, etc. This was basically a very grey market version of child porn, appealing to pedophiles and others. Many of these girls made a ton of money selling pictures of themselves in nearly transparent clothes and other very "question" things for underage girls.
However, as time has gone by, the non-nude market has matured (as have many of the girls) and has settled more and more on being a more teasing version of porn. The girl still don't show off (at least not entirely), but for the most part, the girls are either of a legal age or even in their twenties. Most of the sites avoid the age discussion altogether.