Check BobCat for the journal titles. They are shelved by their call number. For example, MP2 or MP13. Hundreds of printed pages can be condensed onto one microform. One roll can hold several periodical issues.
Periodicals are usually one microfiche sheet per issue.
Microprint or microcard is a reduced image printed on an opaque card. Some items, such as back issues of newspapers, copies of archival materials, or older materials like a facsimile of a 15th century monograph, are not available in any other form. Microforms have made many rare and primary materials readily available to a vast audience. Microform saves valuable space. Back-up copies of some heavily used bound periodicals are kept in microform, in case the volume you need is not on the shelf.