Microfilm refers to a tiny roll of film that stores documents or images in a compact form. It is used to save space and preserve information for a long time. Full definition
The Interlibrary Loan (ILL) Services allow you to obtain print materials, such as books and magazine articles, as well as microfilm of old newspapers, that are not owned within the Westchester Library System. (westchesterlibraries.org)
Alice Trumball Mason loaned records for microfilming in 1959 and in 1969 donated most of those same materials. (aaa.si.edu)
It may be that some durable kind of film will be elaborated on which, in microfilm form, books may be produced and preserved; but so far the film that is used requires very favorable conditions of storage if it is to endure. (religion-online.org)