What is the meaning of Circles?
A doujinshi circle (同人誌サークル), commonly shortened to just circle (サークル), is a group which creates doujinshi. People who are in a circle are called doujinka.
The term "group" can be misleading since circles can consist of only one doujinka. In Japanese fandom, one-person doujinshi efforts are often called kojin circles (個人サークル) or "personal circles", and their products are sometimes referred to as kojinshi (個人誌). These terms have not carried over to English-speaking fandom.
Dōjinshi (同人誌?, often transliterated as doujinshi) is the Japanese term for self-published works, usually magazines, Manga or novels. Dōjinshi are often the work of amateurs, though some professional artists participate as a way to publish material outside the regular industry.