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.
Around this time frame, pornography was also distributed via pornographic Bulletin Board Systems such as Rusty n Edie's.
These BBSes could charge users for access, leading to the first commercial online pornography.
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.
Before publication, Philip Elmer-De Witt used the research in a Time Magazine article, "On a Screen Near You: Cyberporn." Godwin recounts the episode in "Fighting a Cyberporn Panic" in his book Cyber Rights: Defending Free Speech in the Digital Age.
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.