A compzine - coined by contracting compilation and zine - is a zine comprised of pieces written by more than one zinester. Compzines are usually themed, such as featuring pieces by zinesters from the same town, or articles from various zines all published in the same year, or pieces on the same subject.
A typical compzine has one editor who chooses the theme and then either sends out submission calls in the form of fliers, letters and/or posts on online zine communities, or contacts writers and zines where the articles originally appeared. The editor then compiles the submissions she/he receives and prints the compzine.
Contributors are usually listed in the front or back of the zine, with their contact info, and typically receive a free copy of the zine when it's completed.