1 . 2 Browsing the Web
"Surfing the Web," a phrase meaningful a short time ago only to computer geeks, has now entered the popular culture. This is one of the surest signs of the impact of the Web.
According to the WWW FAQ (Frequently Asked Questions) maintained by Thomas Boutell:
What are WWW, hypertext and hypermedia?
WWW stands for "World Wide Web." The WWW project, started by CERN (the European Laboratory for Particle Physics), seeks to build a distributed hypermedia system.
The advantage of hypertext is that in a hypertext document, if you want more information about a particular subject mentioned, you can usually "just click on it" to read further detail. In fact, documents can be and often are linked to other documents by completely different authors much like footnoting, but you can get the referenced document instantly!
To access the web, you run a browser program. The browser reads documents, and can fetch documents from other sources. Information providers set up hypermedia servers which browsers can get documents from.
The browsers can, in addition, access files by FTP, NNTP (the Internet news protocol), gopher and an ever-increasing range of other methods. On top of these, if the server has search capabilities, the browsers will permit searches of documents and databases.
The documents that the browsers display are hypertext documents. Hypertext is text with pointers to other text. The browsers let you deal with the pointers in a transparent way: select the pointer, and you are presented with the text that is pointed to.
Hypermedia is a superset of hypertextit is any medium with pointers to other media. This means that browsers might not display a text file, but might display images or sound or animations.
The compound document a user manipulates is "authored" using the HyperText Markup Language (HTML) which is a specific Document Type Definition (DTD) of the Standard Generalized Markup Language (SGML). In short, the WWW designers wisely chose not to invent yet another language technology and instead chose an existing standardized language.
Initially, HTML was designed simply as a convenient way to mark up text. Shortly after its creation however, the folks at CERN got wind of SGML, and the two have been struggling to stay together. HTML and SGML serve different needs and communities. HTML is geared more toward the look of Web pages, and SGML more toward the documents structure, not how it looks. HTML has benefited greatly from the technology provided by SGML. SGML has benefited greatly from the popularity of HTML and the Web. They have a symbiotic relationship.
The developers of Mosaic used the rich foundation of WWW as a starting point. These collaborations are what make an open Internet such a valuable resource.
Web browsers all have the same basic features. They let you jump from link to link. They display some graphics. They have mechanisms to call other applications for specific media types. Web browser vendors are starting to differentiate themselves by introducing new HTML tags and features. Each vendor hopes its feature set is compelling enough to become the defacto standard for authors. This is a dangerous game and bad for the end user, because documents become tied to specific Web browsers which support the new tags. Standardization and conformance testing offer the only hope for this situation.
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Cello NCSA X NCSA Netscape Spyglass Air Internetwo Win Web
v 1 Mosaic Mosaic (Win) (Win) Mosaic rks Tapes- Explorer
V 2.4 (Win) v 1.0 v 1.02 (Win) (Win) try (Win) (OS/2)
v.20- v 3.06 Beta 4 v 1.67 v.91
alpha3
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COMPLIANCE
proxy + + ~ + + ~ ~
extended html +
PERFORMANCE
multithreading + + +
dynamic linking + +
deferred image + + + +
multi-pane/window / / / / / / +/ /+ /
CONFIGURABILITY
kiosk mode + +
external players + + + +
INTEGRATION
drag&drop to clipboard + +
spawnable players ~ ~ + ~ + + ~ +
search engine +
NAVIGATION AIDS
hotlist/bookmark b h h b h h h b h
folders/categories +/ / +/ +/ / +/ +/ +/+ /
menu/button bar + +
import/export /+ / / +/+ /+ +/+ / +/ /
annotation + + + _ +
auto time/date stamp +
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LEGEND: + indicates that feature is supported in some form
indicates that either the feature is not supported or that we could not get it to function properly
~ indicates that the feature's support was weak by current standards
© 1996 Association for Computing Machinery. Reprinted by permission from "The Client Side of the World Wide Web" by Hal Berghel, CACM Vol. 39, No. 1, Jan. 1996
