Usenet newsgroups provided an early way of sharing images over the narrow bandwidth available in the early 1990s.
Because of the network restrictions of the time, images had to be encoded as ascii text and then broken into sections before being posted to the Alt.binaries of the usenet.
On the Web, there are both commercial and free pornography sites.
The bandwidth usage of a pornography site is relatively high, and the income a free site can earn through advertising may not be sufficient to cover the costs of that bandwidth.
A linklist is a (frequently) categorised web list of links to so called "freesites*", but unlike TGPs, links are provided in a form of text, not thumbs.
It's still a question which form is more descriptive to a surfer, but many webmasters cite a trend that thumbs are much more productive, and simplify searching.
The invention of the World Wide Web spurred both commercial and non-commercial distribution of pornography.
The anonymity made it safe and easy to ignore copyright restrictions, as well as protecting the identity of uploaders and downloaders.
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.
There are several forms of sites delivering adult content.
The main benefit of TGP/MGP is that the surfer can get a first impression of the content provided by a gallery without actually visiting it.
The most abusive form of TGP is the so-called CJ (abbreviation for circlejerk), that contains links that mislead the surfer to sites he or she actually didn't wish to see. Linklists unlike TGP/MGP sites do not display a huge amount of pictures.