Although zines are difficult to classify, there are a few loose categories of zines:
Perzines - stands for "personal zine" are some of the most popular and longest running. perzines focus on personal journeys and thoughts. They are usally very revealing into the personalities of their writers and allow a space for a writer to deal with problems or share experiences
Political - these zines are just that, political. They focus on politics or opinions that the writers feel should be expressed. Many political movements in the united states produce literature this way due to zines ease and flexibility.
Music or Scene- usually focus around music happenings or "scene reports" of a certain area or music genre. These seek to expand the reach of happenings in an area and get people excited about it.
Zines can cover all or none of these categories, these are just some simple classifiers for a great number of zines. If your zine is unclassifiable DON'T PANIC, you're just that good...