A zine (pronounced "zeen," like "magazine") is a self-published, small circulation, non-commercial booklet or magazine, usually produced by one person or a few individuals. Zines are publications done for the love of doing them, not to make a profit or a living. Most zines are photocopied, but their production can range from handwritten or handmade booklets to offset-printed magazine-like publications (but with a print run of hundreds or a few thousand instead of hundreds of thousands).
Zines come in all shapes, sizes, topics, and formats. They can include personal essays, political discussions, fiction, craft or do-it-yourself advice, articles about music or movies, comics, reviews - anything under the sun, really. In a zine, you might find typos, misspelled words, improper grammar, and brilliant or radical or just plain honest ideas that simply aren’t allowed in Time, Newsweek, or People magazine.
Zines, underground press, small press, alternative press … these are just a few of the names for publications that are not produced by a corporation with an eye to the bottom line, but by ordinary people who want to make their voices heard. The underground press is written by street punks and lawyers and stay-at-home moms, and covers topics from politics to fiction to personal observation. At its best, it offers insight into the real lives of the 95% of us who don’t look like the people on TV.
Zines are different from e-zines, which are "zines" published on the Internet (via personal web pages or email lists). More and more, both "zines" and "e-zines" are used to describe these electronic publications. There are significant differences between the two genres; if we say "zine," we mean something on paper.
(definition from the Zine World FAQs page)