This paper discusses the preservation of digital resources in research libraries. The first section addresses the preservation imperative, including the challenges of quantity, stability of media, economics, and the contingent value of artifacts. The second section describes the artifact in question (i.e., an information resource in which the information is recorded on a physical medium, which may or may not be unique, and in which the information value of the resource adheres not only in the text or content, but also in the object itself). Topics covered in this section include definition of the term "artifact," selection for the preservation of the original format, and mechanisms for determining value. (MES)