Digital Libraries on the Internet

The Internet and the Web have been growing in leaps over the past few years, accelerating the problem of information explosion, a well-known phenomenon to all of us. Indeed, search engines (SEs) that have popped up everywhere enable us to access the cyberspace, but they flood us with vast amounts of irrelevant information. Nonetheless, considering the vast amount of information, the Web is considered by many to be the world's ultimate virtual library but is this solution the right one? In any case, the Web and the SEs do not substitute the classical, loved libraries. Looking backwards, libraries can be classified into 3 types: 1) Analog/Paper Library (PL) the classical paper library with its card catalog. 2) Automated/Hybrid Library (AL) an analog library with a computerized catalog. 3) Digital Library (DL) a computerized library in which most of the information is digital. The problems of our regular libraries are well known and need not be detailed here. On the other hand, it is less clear to us what a digital library is and what are its various characteristics. First, we classify the digital libraries into three categories: 1) Single Digital Library (SDL) the regular classical library implemented in a fully computerized fashion. 2) Federated Digital Library (FDL) this is a federation of several independent libraries, centered on a common theme, on the network. 3) Harvested Digital Library (HDL) this is a virtual library providing summarized access to related material scattered over the network. Consequently, we compare the various types of libraries. Moreover, we further discuss aspects of DLs such as personal vs. public libraries and multimedia libraries. Following that, we focus on a comprehensive comparison between HDLs and SEs on the Web. To demonstrate, we show exemplary digital libraries. In particular, we focus on the Katsir HDL, based on the Harvest system, which is currently being developed in Bar-Ilan University as cooperation between the Mathematics and Computer Science department and the department of Information Studies.