There are several forms of sites delivering adult content.
The most common form of adult content is a categorized list (more often it's a table) of small pictures (called "thumbnails") linked to galleries.
At this time the internet was mainly an academic and military network and there was not widespread use of the internet.
One of the early Gopher/FTP sites was at tudelft and was called the Digital Archive on the 17th Floor (List of websites founded before 1995).
These intents to create directories about adult content and websites were followed by the creation of adult wikis where the user can contribute their knowledge and recommend quality resources and links.
When a user purchases a subscription to a commercial site after clicking through from a free thumbnail gallery site, the commercial site makes a payment to the owner of the free site.
A 2015 study finds "a big jump" in pornography viewing over the past few decades, with the largest increase occurring between people born in the 1970s and those born in the 1980s.
While the study's authors note this increase is "smaller than conventional wisdom might predict," it's still quite significant.
A 1995 article written in The Georgetown Law Journal titled "Marketing Pornography on the Information Superhighway: A Survey of 917,410 Images, Description, Short Stories and Animations Downloaded 8.5 Million Times by Consumers in Over 2000 Cities in Forty Countries, Provinces and Territories" by Martin Rimm, a Carnegie Mellon University graduate student, claimed that (as of 1994) 83.5% of the images on Usenet newsgroups where images were stored were pornographic in nature.The anonymity made it safe and easy to ignore copyright restrictions, as well as protecting the identity of uploaders and downloaders.Around this time frame, pornography was also distributed via pornographic Bulletin Board Systems such as Rusty n Edie's.Automated software such as Aub (Assemble Usenet Binaries) allowed the automatic download and assembly of the images from a newsgroup.There was a rapid growth in the number of posts in the early 1990s but image quality was restricted by the size of files that could be posted.