This paper discusses digital libraries on the Internet. The
resource repository hierarchy, consisting of two major paradigms, search
engines (SEs) and digital libraries, is presented. SEs are classified into
three categories: basic-SE, directory, and meta-SE. The following six major
characteristics of a library are summarized: collection of data objects;
collection of metadata structures; collection of services; domain focus;
quality control; and preservation. Three classifications of libraries are
described: the paper/analog library, the automated/hybrid library, and the
digital library. Digital libraries are further subdivided into three
categories, i.e., stand-alone digital library, federated digital library, and
harvested digital library (HDL), and these categories are compared. The
harvesting model for HDLs is discussed, and the Katsir HDL, currently being
developed at Bar-Ilan University (Israel) is described. Differences between
SEs and digital libraries are considered. (Contains 17 references.) (MES)