Traditional journals and libraries have been vital components of scholarly communication. They are evolving, but slowly. The reasons for this are discussed briefly in Section 2.2 and, in more detail, in Odlyzko (1997b). The danger is that they might be rapidly losing their value, and could become irrelevant.
At first sight, there seems little cause for concern. Print journal subscriptions are declining, but gradually. One often hears of attrition in subscriptions of 3-5% per year. For example, the American Physical Society, with high quality and relatively inexpensive journals, has seen a steady decrease of about 3% per year (Lustig, 1997). At those rates, losing half the circulation takes between 14 and 24 years. On Internet time, that is almost an eternity. Preprints in most areas are still a small fraction of what gets published. Also, library usage is sometimes reported as declining, but again at modest rates. Yet these are not reasons for complacency. Why should there be any declines at all? Ours is an information age; the number of people getting college and postgraduate education is growing rapidly, spending on R&D and implementation of new technologies is skyrocketing. Why should established journal subscriptions be dropping, and why should many of the recent specialized journals be regarded as successes if they reach a circulation of 300? Why should many research monographs be printed in runs smaller than the roughly 500 copies of the first edition of Copernicus' De revolutionibus orbium coelestium of 1543?
My conclusion is that the current scholarly information system is badly flawed, and does not provide required services. This paper presents evidence that the demand for high quality scholarly information is indeed growing, and can only be satisfied through easy availability on the Web.
Some of the early studies of electronic usage, such as Lenares' interesting 1999 paper, concentrated on faculty at leading research institutions. Change might be expected to be slow in such places. Although such scholars usually have the resources to be pioneers, they have little incentive, since they have access to good libraries. The evidence to be presented later shows that the current system neglects the needs of growing ranks of scholars who are not at such institutions. Thus, it is better to concentrate on these scholars and their usage of information that is freely available over the Internet.
Tenopir et al. (2000) does show that, among established scholars, electronic resources play an increasing role, but that current usage is dominated by traditional media. However, it is important to look at growth rates rather than absolute numbers. In an early 1999 discussion in a librarians' mailing list, somebody pointed out that, in 1998, only 20% of the astronomy papers were submitted to Ginsparg's xxx paper archive, now called the arXiv, at http://www.arxiv.org . An immediate rejoinder from another participant was that, while this was true, the corresponding percentage had been around 7% in 1995. It is growth rates that tell us what is in our future.
This paper is only a brief attempt at finding patterns in the use of online information. At the moment, we have little data about online usage patterns. This is especially regrettable since these patterns appear to be in the midst of substantial change. What we need are careful studies, such as have been carried out for print media.  Although the Web in principle makes it possible to provide extremely detailed information about usage, in practice there is little data collection and analysis, especially in scholarly publishing. Even when data are collected, they are seldom released. Thus one purpose in writing the initial draft of this paper was to stimulate further collection and dissemination of usage data. The main purpose, though, was to look for patterns even with the limited data available to me, to provide a starting point for further research.
Fortunately, many new studies of electronic resources have appeared recently.  In general, they do support most of the tentative conclusions of this paper, which are:
Usage of online scholarly material is growing rapidly, and in some cases already appears to surpass the use of traditional print journals. Much online usage appears to come from new readers and often from places that do not have access to print journals. 
We can expect the growth of online material to accelerate, especially as the information about usage patterns becomes widely known. Until recently, scholars did not have much incentive to put their works on the Web, as this did not create many new readers. While we can expect that snobbery will retard this step ("I can reach the dozen top experts in my field by publishing in Physical Review Letters, or by sending them my preprint directly, why do I care about the great unwashed?"), the attraction of a much greater audience on the Web and the danger that anything not on the Web will be neglected are likely to become major spurs to scholars making their works available online. For example, the recent study by Lawrence (2001) shows that papers in computer science that are freely available online are cited much more frequently than others. Anderson et al. (2001) might appear to suggest the opposite, since in this study free online availability was associated with lower citation frequency. However, that result is likely anomalous, in that the freely available online-only articles in the journal under study were apparently perceived widely, even if incorrectly, as of inferior quality.
The need for traditional peer review is overrated. Odlyzko (1995) had extensive discussion of the inadequacy of conventional peer review, and how much more useful forms were likely to evolve on the Internet. That paper was written before the ascendancy of the Web. While open review and comments on published papers have been slow to take hold, online references and bibliographies are developing into a new form of peer review. People are coming to my Web page in large numbers looking for specific papers. While in almost all cases I do not know what brings them there, it is pretty clear that they are finding links to the material in a variety of sources, such as bibliographies and references on other home pages. A new form of peer review, it brings many readers even for papers published in obscure and unrefereed places.
Concerns about information overload and chaos on the Net are exaggerated. While better organization of the material would surely be desirable, people are finding their way to the serious information sources in growing numbers as is.
Ease of access and ease of use are paramount. Material on the Web is growing, and scholars, like the commercial content producers, are engaged in a war for the eyeballs. Readers will settle for inferior forms of papers if those are the ones that can be reached easily.
Novel forms of scholarly communication are evolving that are outside the boundaries of traditional journals.
These conclusions and predictions are supported by data in the rest of this paper. It does appear that while journals are not changing fast, scholarly communication as a whole is evolving rapidly.