Preservation is an applied science that is focused on maintaining characteristics of an artefact (such as information in physical or digital form) with minimal degradation. Characteristics may include physical state (as in preserving the viability of a document of long term value) or meaning (as in the authenticity of the content of a record).
Microfilm is a common example of a method to preserve meaning, but not original form. Under proper conditions (i.e. within temperature, humidity and handling tolerances) microfilm can retain meaning with no discernible loss of integrity for 500 years. Problems encountered with microfilm repositories are almost inevitably a result of inadequate process and retention management.
Digitization for the same purpose is attractive where the concurrent distribution of meaning is required. However, as a long term retention medium, digital records create additional, manageable challenges. See: fixity.
Such strategic considerations are the purview of Certified Records Managers and others who advise on a governance framework for all media with in an operational context.