Imagine you are reading a magazine article about great white sharks, and you come to a sentence about the shark's teeth. You think to yourself, "I'd like to learn more." You push on the word "teeth" in the page and an expert from Australia's Great Barrier Reef pops up in the magazine -- complete with a full-color graphic, or video, or sound -- and describes how the many rows of teeth renew themselves and push forward as old ones are broken or lost. Next you link to a reference in Florida on the best beachcombing spots to find teeth. On and on you link by pressing words in the text, learning more about great whites, teeth, beaches, or any topic you care to search. Sound improbable? It's not. In a nutshell that's how NCSA Mosaic, a software graphical-interface browser for the Internet, retrieves and displays information. One mouse click on a certain word in a sentence or a designated area in an illustration, and the viewer is transported around the world to a referenced piece of information, complete with graphics presented in magazine-page format. In effect, NCSA Mosaic is like a tour guide to the Internet. It makes all the arrangements, speaks all languages, and knows all the best sights. It provides an open, unified interface to all the diverse information archives, data protocols, and data formats of the Internet. Extremely userfriendly, NCSA Mosaic is now in widespread use, with some 2 million systems In place. It is currently being acquired at a rate of at least 100,000 copies per month. What's more, it can be downloaded off the Internet for free from the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign, where it was developed. NCSA Mosaic was first introduced on the UNIX platform in January 1993. By May 1993 volume (bytes transmitted) had risen a hundredfold on the key Information system that NCSA Mosaic accesses, the Internet's World Wide Web (WWW). Macintosh and PC versions were introduced in August 1993, and by May 1994 WWW volume had increased a hundredfold again. And the trend is upward. Anyone who is waiting for the information highway to open can stop waiting! To grasp the value of NCSA Mosaic, one must first appreciate the Internet and some of its earlier information systems. The Internet can be viewed as a gigantic information space, in which you can discover and retrieve data, documents, images, audio/video, and a host of other resources and services from a worldwide collection on some 3.25 million host computers. If you knew where everything was, all you'd have to concern yourself with would be accessing information from those known addresses. What's needed, however, is a way to search for information when the sources are unknown. These software mechanisms exist and in Internet parlance are called browsers or search engines. The original method of acquiring information on the Internet was by file transfer protocol (FTP), in which the user knew what he or she wanted and where it was. Accessing this information required knowledge of basic command language. Browsers and information systems then appeared to facilitate key-word searches, including text-based Gopher (from the University of Minnesota), and WAIS (wide-area information services), both a bit dry and lacking interconnections. Then came the WWW, the information system opened by NCSA Mosaic. The WWW was created in 1990 at the CERN Laboratory for Particle Physics in Geneva, Switzerland. It was designed originally as an electronic library to facilitate sharing and retrieval of information among the scientists there. What distinguishes the web, as it is called, is its system of hypertext links embedded in richly formatted documents, used here generically to include text, fullcolor images, video, and sound. To create the byperlinks, each author who added information to the web also referenced related works from researchers around the world, and linked them in his or her document by the computer address code at the server holding the referenced information. (Computers where information is located are called servers or hosts. Those used to call up and display information -- UNIX machines, PCs, or Apple Macintosh -- are called clients.) The references are linked at the word relating to the reference. For instance, in the great white shark example, the word "teeth," highlighted in blue and underlined in the NCSA Mosaic format, is the door that opens the author's selected references on teeth. In NCSA Mosaic, the user simply clicks on the word and the referenced document is retrieved from anywhere in the world. "Researchers could point hyperlinks at one another's material, thereby building an aggregation of knowledge that's not just strictly by one author," says Larry Jackson, NCSA Mosaic project manager. "A good analogy is the bibliography of a book. It tells you the author's favorite references." That is, only references chosen by the author are linked. A significant feature of NCSA Mosaic is the way it presents information -- that is, embedded graphics. Before NCSA Mosaic, if an author hyperlinked to a reference containing images, viewing the illustration required interrupting the view of the text to bring the image up on a separate screen. NCSA Mosaic presents the illustrations directly in the text of the document, magazine-format style. NCSA Mosaic is also a multiprotocol system. This means it is capable of following links into the information systems that preceded WWW -- namely, FTP, WAIS, Gopher, and Newsgroups, a bulletin-board system. These systems are not hypertext linked, nor do they include in-line graphics. But information on servers in these systems can be reached with NCSA Mosaic, and WWW documents can contain links into these other systems. "The point is, you don't have to have seven or eight different clients on your desktop depending on what kind of file you're looking at," says Mr. Jackson. "Whatever the protocol, wherever the location, whatever the format, compressed or not, NCSA Mosaic can handle it." Companies are beginning to recognize the commercial opportunities of being on-line on the Internet, which had some 35 million worldwide users as of October and is growing at a rate of 15% per month. Businesses can distribute information and provide support to dealers and customers, make business-to-business and retail transactions, even publish. Those wishing to use NCSA Mosaic as their interface, however, need a different version than the Internet freeware. Copyrighted by the University of Illinois, by law NCSA Mosaic can only be downloaded for free by individuals and by companies wishing to use the Internet as a network for internal communications. Also, NCSA is not set up to serve as a support desk for commercial use of the program, which, according to Mosaic program manager Mr. Jackson, is "an uncontrolled experiment." NCSA Mosaic is in a constant state of revision, with new releases offered every few weeks. "If a company is going to use it in a 'bet your business' situation," says Mr. Jackson, "they'll want more support than we can give them. They need a more rugged version, a help desk, and they may need NCSA Mosaic mutated slightly to meet specific requirements." These openings have created a market for NCSA Mosaic licensees, companies that enhance the product and provide the services to support its use in commercial endeavors. Though some companies hold licenses from previous arrangements, in August 1994 the University of Illinois assigned future commercial rights for licensing NCSA Mosaic to Spyglass Inc., Champaign, Ill. This company is licensing Enhanced NCSA Mosaic by the millions to hardware vendors, networking software vendors, and on-line service providers who add value and incorporate the software into their products, including IBM Networked Systems Div., Digital Equipment Corp., AT&T Corp., Firefox Software Inc., FTP Software Inc., NEC Systems Laboratory Inc., O'Reilly & Associates Inc., and Walker, Richer & Quinn. In October GE Plastics jumped on the Internet with the help of Internet In A Box, a commercial version of NCSA Mosaic from early NCSA Mosaic licensee Spry Inc., Seattle. GE Plastics will make available more than 1,500 pages of corporate and product literature, press announcements, photography, design guides, and other key information from a WWW server at GE's corporate R&D center.