The World Wide Web is a system of Internet servers that supports hypertext to access several Internet protocols on a single interface. The World Wide Web is often abbreviated as the Web, WWW, or W3.
The World Wide Web was developed in 1989 by Tim Berners-Lee of the European Particle Physics Lab (CERN) in Switzerland. The initial purpose of the Web was to use networked hypertext to facilitate communication among its members, who were located in several countries. Word was soon spread beyond CERN, and a rapid growth in the number of both developers and users ensued. In addition to hypertext, the Web began to incorporate graphics, video, and sound. Over the past few years, the use of the Web has reached global proportions.
Almost every protocol type available on the Internet is accessible on the Web. Internet protocols are sets of rules that allow for intermachine communication on the Internet. The following major protocols are accessible on the Web:
Producing hypertext for the Web is accomplished by creating documents with a language called HyperText Markup Language, or HTML. With HTML, tags are placed within the text to accomplish document formatting, visual features such as font size, italics and bold, and the creation of hypertext links. Graphics may also be incorporated into an HTML document. HTML is an evolving language, with new tags being added as each upgrade of the language is developed and released. The World Wide Web Consortium, led by Tim Berners-Lee, coordinates the efforts of standardizing HTML.
Web pages can be created by user activity. For example, if you visit an Internet search engine and enter keywords on the topic of your choice, a page will be created containing the results of your search.
Access to Web pages may be accomplished by:
URLs are translated into numeric addresses using the Internet Domain Name System (DNS). The numeric address is actually the "real" URL. Since numeric strings are difficult for humans to use, alphneumeric addresses are employed by end users. Once the translation is made, the Web server can send the requested page to the user's Web browser.
Anatomy of a URL
This is the format of the URL:
protocol://host/path/filenameFor example, this is a URL on the home page of the U.S. Census Bureau
http://www.census.gov/pubinfo/www/news.htmlThis URL is typical of addresses hosted in domains in the United States.
telnet://library.albany.edu the University at Albany library catalogSeveral top-level domains (TLDs) are common in the United States:ftp://bongo.cc.utexas.edu/microlib a file at an ftp site
| com | commercial enterprise |
| edu | educational institution |
| gov | U.S. government entity |
| mil | U.S. military entity |
| net | network access provder |
| org | usually nonprofit organizations |
| ch | Switzerland |
| de | Germany |
| jp | Japan |
| uk | United Kingdom |
An international consortium had originally proposed adding seven new domain names, as follows:
| firm | businesses or firms |
| store | businesses offering goods to purchase |
| web | entities emphasizing activities related to the WWW |
| arts | ntities emphasizing cultural and entertainment activities |
| rec | entities emphasizing recreation/entertainment activities |
| info | entities providing information services |
| nom | those wishing individual or personal nomenclature |
You can install a graphical browser such as Netscape Navigator in your Windows-based or Macintosh machine. Navigator is available for downloading on the Netscape home page: http://home.netscape.com. To use the program to access the Web, you need an ethernet connection or a dialup connection known as a SLPP or PPP. The latter may be obtained from an Internet Service Provider. For more information, see How to Connect to the Internet.
File formats requiring helper applications are known as MIME types. MIME stands for Multimedia Internet Mail Extension, and was originally developed to help e-mail software handle a variety of binary (non-ASCII) file attachments. The use of MIME has expanded to the Web. For example, the basic MIME type handled by Web browsers is text/html associated with the file extention .html.
A common helper application utilized on the Web is the Adobe Acrobat Reader. The Acrobat Reader allows you to view documents created in Adobe's Portable Document Format. These documents are the MIME type application/pdf and are associated with the file extension .pdf. When the Acrobat Reader has been configured to your browser, the program will open and display the file requested when you click on a hyperlinked file name with the suffix .pdf.
Plug-ins are software programs that extend the capabilities of a Web browser in a specific way, such as the ability to play audio files or view video movies from within Navigator. Web browsers are often standardized with a small suite of plug-ins. Additional plug-ins may be obtained at the browser's Web site, at special download sites on the Web, or from the home pages of the companies that created the programs. The number of available plug-ins is increasing rapidly. Nearly 200 plug-ins are available for downloading at the Netscape site.
Once a plug-in is configured to your browser, it will automatically launch when you choose to access a file type that it uses.
Netscape Communicator can be downloaded with a variety of helper applications and plug-ins configured to the browser, including:
The problem of slow download times has been answered by a revolutionary development in multimedia capability: streaming data. In this case, audio or video files are played as they are downloading, or streaming, into your computer. Only a small wait, called buffering, is necessary before the file begins to play. The RealPlayer plug-in plays streaming audio and video files. Extensive files such as interviews, speeches and hearings work very well with the RealPlayer. The RealPlayer is also ideal for the broadcast of real-time events. These may include press conferences, live radio and television broadcasts, concerts, etc. A list of sites that make use of the RealPlayer is available at http://www.albany.edu/library/internet/net_info/realaudio.html.
Shockwave presents another multimedia experience. Shockwave allows for the creation and implementation of an entire multimedia display combining graphics, animation and sound.
Sound files, including music, may also be heard on the Web. It is not uncommon to visit a Web page and hear background music. Sound files are also available for downloading independent of Web page visits. Sound files of many types are supported by the Web with the appropriate helper applications.
Live cams are another aspect of the multimedia experience available on the Web. Live cams are video cameras that send their data in real time to a Web server. These cams may appear in all kinds of locations, both serious and whimsical: an office, on top of a building, a scenic locale, a special event, and so on.
What follows is a basic guide to a group of the more important languages in use on the Web today.
CGI, Active Server Pages: CGI (Common Gateway Interface) refers to a specification by which programs can communicate with a Web server. A CGI program, or script, is any program designed to accept and return data that conforms to the CGI specification. The program can be written in any programming language, including C, Perl, and Visual Basic. A common use for a CGI script is to process an interactive form on a Web page. For example, you might fill out a form ordering a book through Interlibrary Loan. The script processes your information and sends it to a designated e-mail address in the Interlibrary Loan department.
A newer type of dynamically generated Web page is called Active Server Pages (ASP). Developed by Microsoft, ASPs are HTML pages that include scripting and create interactive Web server applications. The scripts run on the server rather than on the Web browser to generate the HTML pages sent to browsers. Visual Basic and JScript (a subset of JavaScript) are often used for the scripting. ASPs work with only Microsoft's Web servers.
Java/Java Applets: Java is probably the most famous of the new programming languages of the Web. Java is an object-oriented programming language similar to C++. Developed by Sun Microsystems, the aim of Java is to create programs that will be platform independent. A perfect Java program should work equally well on a PC, Macintosh, Unix, and so on, without any additional programming. This goal has yet to be realized. Java can be used to write applications for both Web and non-Web use.
Web-based Java applications are usually in the form of Java applets. These are small Java programs called from an HTML page that can be downloaded from a Web server and run on a Java-compatible Web browser. A few examples include live newsfeeds, moving images with sound, calculators, charts and spreadsheets, and interactive visual displays. Java applets can tend to load slowly, but programming improvements should lead to a shortened loading time.
JavaScript/JScript: JavaScript is a programming language created by Netscape Communications. Small programs written in this langauge are embedded within an HTML page to enhance the functionality of the page. Examples of JavaScript include moving tickers, drop-down menus, real-time calendars and clocks, and mouse-over interactions. JScript is a similar language developed by Microsoft and works with the company's Internet Explorer browser.
VRML: VRML (Virtual Reality Modeling Language) allows for the creation of three-dimensional worlds. These may be linked from Web pages and displayed with a VRML viewer. Netscape Communicator comes with the Cosmo viewer for experiencing these three-dimensional worlds. One of the most interesting aspects of VRML is the option to "enter" the world and control your movements within the world.
At its simplest, chat programs allow multiple users to type to each other in real time. Internet Relay Chat and America Online's Instant Messenger are prime examples of this type of program. The development of a messenging protocols is underway. Such a protocol would allow for the expansion of this capability throughout the Internet.
More enhanced real-time communication offers an audio and/or video component. CU-See Me is one of the most popular sotware programs of this type. Even more elaborate are programs that allow for true real-time collaboration. Microsoft's NetMeeting and Netscape's Conference (available with Communicator) are good examples of this.
Featured collaboration tools include:
Push: Push refers to a technology that sends data to a program without the program's request. This is the opposite of the typical "pull" of the Web, in which the user clicks on a link to request a file from a server. With push, the data is sent automatically. Content is sent through a "channel." The early Web-based implementation of push was commercial. Probably the best known example is PointCast, which sends customized news to users' desktops in the form of a screen saver. Push can also be used to deliver software upgrades to a desktop machine.