Usually manga or novels, that are self published by amateurs, though professionals do use this form as well.
Reference to self published amateur authors and artists, who are producing Anime, Hentai, and Games.
However, they aren't limited to those specific endeavors.
Some professionals will also be part of this collection, as they seek other venues to display their works, or to explore other fields of work or genres.
The word is derived from Dojin and Shi (a contraction of the word zasshi).
Dojin refers to self, or those who share a common interest, goal.
Shi refers to magazine, well the original meaning is, this is a contraction of that word.
Groups of Dojinshi called themselves 'a circle'.
In some instances, several such groups, can be simply of one artist or author, and are known as Kojin Circles (personal circles)
More aptly these groups or circles convene in various locations, to sell their products. Sort of like a public market.
Practice (Associated Acts):
Some of the works, offered by self published authors/artists are low in production, as they are based on existing published works.
Trading of these self published works, occurs in huge markets, or trade events.
The largest is called Comikat and is held twice a year.
It covers 20 acres, where stalls and such are set up, selling these self published works.
Like any comic book convention, massive trading goes on for special editions, for limited editions, etc.
During the 1980's the focus shifted from being a majority of self published original works, to becoming a parody or copy of existing works.
This change, has also created an enormous fan base, as the number of copies are usually limited, to avoid lawsuits or legal ramifications.
Advances in personal computing and software, has allowed for an explosion in this market, during the last decade or so.
Many now offer download abilities, online sales, and even compact disc editions.
In some way, many look on this as a method of learning the art, to practice before entering the more commercial aspect of the industry.