Successful websites get a lot of traffic, and usually there is a skilled SEO behind this. Its hard to have an online business with no visitors, which is why the first websites were directories that listed different content websites on the web. The adult industry had always been underground, and took to the web like a hungry dog on a meat wagon. But while the adult industry helped monetize the web, SEO’s helped organize and elucidate good mainstream content.
In 1841, William Fox Talbot patented the calotype process, the first negative-positive process, making possible multiple copies [of photographs]. This invention permitted an almost limitless number of prints to be produced from a glass negative. Also, the reduction in exposure time made a true mass market for pornographic pictures possible. The technology was immediately employed to reproduce nude portraits. Paris soon became the centre of this trade. In 1848 only thirteen photography studios existed in Paris; by 1860, there were over 400. Most of them profited by selling illicit pornography to the masses who could now afford it. The pictures were also sold near train stations, by traveling salesmen and women in the streets who hid them under their dresses.
— wikipedia
The first linkerati were adult webmasters who judiciously linked between their websites and traded traffic with unabashed abandon. It is almost like a potlatch to see who can send their associates the most traffic. The underlying reason is that porn surfers are notoriously fickle and rarely buy, so instead of loosing a live visitor, send them to your buddy. These traffic and link trades have been replicated in some part by bloggers, but pornographers are the true linkerati.
