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Selasa, 06 Januari 2009

What Is the World Wide Web?


The History of the Web

Of all the worthwhile features of the Internet, none has captured the public's imagination and contributed to the Net's growth so much as the World Wide Web. A method of posting and accessing interactive multimedia information, the "Web" is a true "information superhighway," allowing users the world over to access a wealth of information quickly and easily.

The History of the Web

The first rumblings toward this concept began immediately after World War II, when scientists were desperately seeking ways to organize and share their accumulated wartime research. In 1945, noted scientist Vannevar Bush published an essay in Atlantic Monthly titled "As We May Think," which proposed a massive information index that people from all over the world could access and search. Although Bush's system was mechanical (and was never developed), his essay had a profound impact on many who would one day help design the Internet and the World Wide Web. For this reason, Vannevar Bush is often hailed as the theoretical father of the Web.

Given this background, the actual Web was originally conceived as a way for physicists to share their research data. In 1989, Tim Berners-Lee led a team at Switzerland's European Particle Physics Laboratory (CERN) in developing the initial World Wide Web standards. Key among these was the use of hypertext, or "hot" portions of an online document that, when selected, take the user to a related, or "linked," document. For instance, if a user was reading a Web document about dinosaurs and selected the hypertext word "Tyrannosaurus," he or she would go directly to a document dealing specifically with that species of dinosaur.

Try it! Click on Tyrannosaurus and see what happens...

Computerized hypertext was pioneered by researcher Ted Nelson in a system called Xanadu, which he created in the early 1960s. Although Xanadu was never fully realized, many of the Web's developers—including Berners-Lee—have cited it as an influence on their work.

The next great innovation for the Web came in 1992, when programmers from the National Center for Supercomputing Applications (NCSA) at the University of Illinois developed the Mosaic browser, a software application that displayed not only the text of a Web document (or page), but embedded graphic elements as well. By bringing multimedia to the Web, Mosaic vested it with enormous potential.

Today, several Web browsers are available for IBM, Macintosh and UNIX-based computers, and most of the major online services include Web browsers in their standard software packages. And the Web is growing at a phenomenal rate. According to Interactive Week magazine, the number of Web servers (computers that store Web pages) surged from fewer than 3,500 in April 1994 to more than 40,000 in July 1995. And in February 1997, the computing firm Network Wizards determined the number of commercial domains alone to be well over 700,000.

What Else Makes the Web Unique?

We have already cited hypertext and multimedia as two of the outstanding features of the World Wide Web. Among the Web's other distinct advantages are:

  • Open standards that allow Web pages to be viewed through most any computer with an Internet connection and a Web browser.
  • The ability to make software and data files available for downloading.
  • Ease of use; just point and click on your browser to access the information you need.

For the individual or organization wishing to distribute information, the Web makes "publishing" easy and cost-effective. Putting information on the Web is quite inexpensive compared with traditional publishing, yet puts that information before a potential audience of millions. And unlike a printed publication, a Web document can be revised and updated at any time.

What Does the Web Empower Me to Do?

The World Wide Web brings you all of the advantages of the Internet—and more! Among the things that the Web allows you to do are:

A Quick Tour of a Typical Web Site

A Web site may consist of a single Web page, or may comprise multiple, interconnected pages. The following is a view of how the CenterSpan home page appears through a popular browser:

CenterSpan home page

  1. Browser tools help you navigate around the Web. These vary among browsers, but most include tools for moving back and forth between pages, saving data to your hard disk, and controlling how Web pages will appear on your screen.
  2. A "Bookmark" list, "favorites" list or "hotlist" lets you save the names and locations of favorite sites for easy reference (usually accessible through pull-down menus).
  3. The Uniform Resource Locator (URL) is the address of a Web site. URLs for Web pages begin with the code http:// ("http" stands for hypertext transfer protocol).
  4. Some Web pages contain special graphic buttons that, when clicked, take you to another resource as would a regular hotlink.
  5. Hypertext hotlinks are connections to other pages and resources. To access, just click on them with your mouse or trackball. Most pages contain hotlinks throughout the text, as well as lists of links to other sites judged by the author/sponsor to be of particular interest. Some sites contain hotlinks to places where you can download software, listen to a sound file, or view a video clip.
  6. CenterSpan uses several applets, or small program segments run by Java, ActiveX or some other protocol. Applets are downloaded when you access a Web site, and run only as long as you remain at that location. Applets can perform a variety of functions; the applet on the CenterSpan home page generates a scrolling banner, like the example below:

    If your browser does not have the capability to display Java applets, you will not be able to see this banner.
  7. To make it easy to contact the author or sponsor of a Web site, most contain one or more E-mail links. Clicking on such a link brings up a form where you can type an E-mail message to a pre-set address (not shown here).

CenterSpan is among more elaborate Web sites that contain forms, where you can submit information in an easy-to-follow format, and bulletin board features that allow you to post information for others to see.

Source:http://www.centerspan.org/tutorial/www.htm
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How to Connect to the Internet and World Wide Web

In this section...

Before you can connect to the Internet and access the World Wide Web, you need to have certain equipment. In brief, you must have a computer (preferably running an up-to-date operating system); a modem and access to a telephone line or a local area network (LAN) that is in turn connected to the Internet; and connection software that will allow you to establish an account with a service provider and access the Internet.

A modem is not needed when accessing the Internet through a LAN.

The Right Hardware

To operate most of the current Web browsers and on-line services, you should have an IBM PC/PC equivalent, UNIX workstation, or Apple Macintosh computer with at least 8 megabytes (MB) of random access memory (RAM) and 10 MB of free disk space. If you are unsure of how much RAM and disk space your computer has, consult your user's manual.

NOTE: Although the capacities of both are measured in megabytes, RAM and disk space are NOT the same thing! RAM refers to the electronic microchips in your computer that store data for relatively brief periods, and that give your computer the active capacity to run programs and access data. Disk space refers to space on the magnetic hard disk inside (or connected to) your computer that stores data over the long term.

For best results, use a PC with a 486 or Pentium microprocessor; or a Macintosh with an 030, 040 or PowerPC microprocessor.

It is possible to connect to the Internet using a computer other than an IBM PC, Macintosh or UNIX workstation, though the access software available for such machines is limited.

If you are accessing the Internet outside of a LAN environment, you will need a modem that will connect you with other computers and interpret the data being sent back and forth. Most any modem that is compatible with your computer will do, though the higher the kilobits per second (kbps) rate of your modem, the faster it will transmit data. Modem speed is an important consideration when accessing sites on the Web that contain lots of digitized data. In general, your modem should transmit data at 14.4 kbps or faster to give you optimum performance on the Web. If you are looking to purchase a modem, buy the fastest model you can afford.

You must also have access to a live telephone line. Most modems accept the same jacks as do ordinary household telephones, allowing you to connect your modem to a wall jack using standard phone cord. Some cable TV providers have begun offering Internet connections via cable. Such connections provide much faster transmission speeds than standard phone lines, though you will need a special modem that allows you to link your computer with the cable. If you are interested in a cable Internet connection, contact your local cable operator to see if the service is available in your area.

You can also connect to the Internet through a LAN with Internet access. If you are unsure as to the capacities of your LAN to do this, contact your site's systems administrator.

The Right Software

For best results, make sure that your computer is running the most up-to-date operating system that it can handle. If you have an IBM PC/PC compatible computer, it should be running Microsoft Windows version 3.1, Windows NT, Windows 95 or OS/2. If you have a Macintosh, it should be running System 7 or higher.

To make your connection complete, you will need connection software that allows your computer to dial into an Internet access provider, establish an account, and work with the data in a straightforward manner. Many access providers will give you software that will allow you to access their systems using an all-in-one custom interface. Others may give you a collection of separate software packages that can be used together. But whatever software they provide, be sure that it is compatible with your computer and operating system before attempting to use it.

Some Internet access providers may allow you to establish a serial line interface protocol (SLIP) or point-to-point protocol (PPP) connection, either of which essentially makes your computer a part of the Internet. Unlike many standard dial-up software packages, a SLIP/PPP connection allows you to run independent software packages such as Web browsers, either one at a time or simultaneously.

The Browser

As you surf the Web, you will come across sites that state, "This site is best viewed with…" and then name a particular browser. Many will even provide a link to a site where you can download the specified browser.

Sites make these recommendations because some browsers use special protocols, allowing site creators to offer extra features beyond the standard capabilities of hypertext markup language (HTML). Chief among these browsers are Netscape Navigator and Microsoft Internet Explorer.

Your Internet service provider will most likely give you a choice of browsers (if you have a SLIP/PPP account, you may use any browser you wish), so try out a couple, and use the browser that best suits your needs.

Extras

The Netscape Navigator and Microsoft Internet Explorer browsers allow for the use of plug-ins, or extra software applications that run as if they were an integral part of the browser. To see which plug-ins are currently available for Netscape, go to: http://home.netscape.com/comprod/mirror/index.html To see the plug-ins for Internet Explorer, go to: http://www.microsoft.com/ie/download/

Browsers also use helper applications that, while not as integral as plug-ins, enhance the browser's capabilities by launching when needed. Helper applications allow your browser to play sound and video files, display animation and other graphic formats, or access special Internet features such as TELNET. Most Web sites that require the use of helper applications will provide links to sites where you can download the necessary software.

For more information on plug-ins and helper applications, go to the "Useful Links" section.

Connection Options

Until recently, the two primary methods of accessing the Internet were through a network connection, allowing users of local area networks (LANs) to go online through their school or workplace systems, and dial-up connections through a modem and phone line. However, new connection options allow for greater speeds and flexibility, while keeping costs to a minimum.

The following are some of the newer connection options that you might want to investigate:

  • Cable Internet—These systems allow your computer to connect to the Internet through the same cable that carries your TV signal. Monthly service charges are usually not much more than standard modem connection costs, but you have to rent or purchase a "cable modem." Additionally, your computer will need an Ethernet card (a special circuit board that allows for network connections). Not all cable service operators offer this service; call your local operator for more information.
  • Satellite connections—DirecPC (http://www.direcpc.com/) allows you to download Internet files via a satellite connection. This is an efficient method for receiving large Web graphics and other items, but you still need a modem connection for other features. You must purchase the connection hardware as well as subscribe to the service.
  • Integrated Services Digital Network (ISDN)—An ISDN line is a type of digital phone line that can transmit data many times faster than a conventional modem and phone line. To learn more about ISDN, go to http://www.isdn.ocn.com/index.shtml
  • Wireless connections—Pagers, cellular phones and personal digital assistants (PDAs) now allow varying levels of Internet access, from notification of E-mail to limited Web connections. Many of these services remain in the experimental stage.
  • WebTV—Introduced in late 1996, WebTV (http://www.webtv.net/) provides Web and E-mail access through ordinary television sets. The connection is made through a custom high-speed modem. You must purchase a special set-top unit for your TV, plus subscribe to the connection service. Recently, similar systems by other manufacturers have appeared on the market to compete with WebTV.

Locating Internet Access Providers

If you already have Internet access but wish to learn about other access providers, go to TAG Online (http://www.tagsys.com/Provider/provider_search.html) or Mecklermedia's "The List" (http://www.thelist.com/), where you will be able to search databases of U.S. and international access providers by name, geographic location and area code.

If you do not already have Internet access, you can learn about Internet services that are available in your area by contacting your local library or telephone company for recommendations, or by consulting a local computer publication or computer store.

For information about international Internet access, see the section "The 'Net Around the World."

What to Look for in an Access Provider

Access providers vary widely in the services and capabilities they offer. The providers listed at the beginning of this chapter offer local access throughout most of the United States; however, you might find that a smaller, local provider is more suited to your needs.

Before committing to a service of any kind, be aware of the following variables:

  • Fee plan—Providers may offer a flat monthly fee for unlimited access, a metered hourly fee, or both. The fee that will be most reasonable for you depends on how much time you plan to spend online. If you are online for more than five hours per month, a flat monthly fee will be the most economical choice. Otherwise, you'll be paying for service you don't need.
  • Start-up fees—Some providers charge a fee for setting up new accounts that can range from a few dollars to $100. Providers may also charge "hidden" fees and premium rates for access at certain times. Ask for a breakdown of all fees charged before you sign on.
  • Local access numbers—Unless you can dial in from your local area, you'll be paying long distance charges for each Internet session. Make sure a provider offers access numbers for your area, as well as for any area to which you routinely travel.
  • Contracts—You may be offered a yearly or multi-year contract for service in exchange for a discount rate. However, if you cancel your account before the contract is up, the provider might charge you a penalty. Also, make sure that your service provider is stable and reliable before committing to a long-term agreement, particularly if you are required to pay up front.
  • Dependable access—The ability to establish a connection during peak hours has become an important issue as more people go online. A good service provider, obviously, should have few busy signals and minimal downtime.
  • Good customer support—If you call with a question concerning your account at an odd hour, will your call be taken? Will your E-mail queries be answered? The major providers usually have excellent customer support, but smaller outfits may offer little or no support services. Also be alert to premiums charged for support calls.
  • Proprietary services—America Online, Prodigy and CompuServe all have their own databases, conference centers and chat rooms not available on the Internet or any other service. Other service providers offer nothing more than a straight connection to the Internet.
  • Restricted access—Providers can often determine what Internet services they will provide. For example, some will carry only selected newsgroups. Providers that lack such restrictions often advertise their "uncensored" and "unrestricted" access.
source:http://www.centerspan.org/tutorial/connect.htm
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Surfing the Web for the First Time

In this section...

Getting Online

Once you have established your Internet account, you are now ready to "surf" the World Wide Web from your computer. To do so, perform the following steps (specific instructions will vary depending on your access provider and software):

  1. Start up your computer, and make sure that your modem is on and connected to a telephone line.
  2. Open your access software.
  3. Initiate the connection. Many access software packages will display the status of the connection process, which generally takes between 15 and 30 seconds.
  4. Once you have successfully connected, access and launch your Web browser.

If you have successfully accessed the Web, you will see in your browser window the home page, or the first page that your browser is set to access. Often the home page is a site belonging to the manufacturer of the Web browser you're using. On most browsers, you can change the home page to a site that you'd like to access each time you begin a Web session.

Depending on the speed of your modem and the size or complexity of the page you're accessing, the time necessary to completely load a page can range from a few seconds to several minutes.

Finding Your Way Around

Now that you've gotten on the Web, you're probably wondering how to get to all those great resources that you've been hearing about. Fortunately, there are several strategies for moving about the Web:

  • Type the URL address of a site into the entry field of your browser.

Try it! Type the complete URL for the CenterSpan Web site below, then click on the "Go!" button:

This is the most basic method of accessing a Web site. However, you have to know exactly where you want to go, and then type in the address precisely in order to get there. The newer browsers can compensate for some typing (for instance, allowing you to omit the "http://" at the beginning of a URL), but some URLs are too complicated for a browser to second-guess.

If you simply want to explore and get to know the Web, any one of the following strategies are preferable:

  • Click on hyperlinks to move among resources; your home page probably has some links to interesting sites.
  • Access a jump site, which is a page consisting mainly of categorized hotlinks to other sites. Again, your home page may function as a jump site.
  • Access a Web index, which lets you access sites by typing in keywords.

Jump sites contain collections of special-interest sites that the author has included for certain reasons. Web indexes, however, usually contain much more eclectic assemblies of Web resources. If you're on the Web and are not sure where to go, head to the nearest Web index.

Using a Web Index

To access and use a Web index, perform the following steps:

  1. While logged on to the Web, type http://www.yahoo.com/ in your browser's URL entry field.
  2. Press ENTER or RETURN on your keyboard.

This will take you to Yahoo!, one of the most popular Web indexes. Underneath the Yahoo! logo, you will see a blank search entry form, as well as hotlinks of site categories.

  1. Click on one of the category topics and follow the categories until you reach a site that matches your interests.

...OR...

  1. Click your mouse in the entry form. This will place a blinking cursor in the form.
  2. Type one or more words pertaining to information you'd like to locate on the Web.
  3. Click on the SEARCH button to the right of the entry form, or press RETURN or ENTER on your keypad.

    After a few seconds, Yahoo! will return with a list of hotlinks that match your search criteria. The more specific your criteria, the fewer and more specific hotlinks you will see.
  4. Scroll down the page and select the hotlink to a page that you'd like to explore [NOTE: Extensive search results will take up multiple pages].

If you would like to try searching with a Web index other than Yahoo!, select one of the index hotlinks listed at the bottom of each page of search results. When you select any one of these indexes, the keywords you entered for Yahoo! will remain in force, though the search results will be different simply because of the way that each Web index processes information.

How Do Web Indexes Know What They Know?

It would seem that cataloguing everything on the Web would be a monumental and maddening task. Web indexes meet this challenge using two primary strategies.

One way of building an index is to let the site creators register their sites with the index, in order to generate publicity for their sites. The other is to use special software that automatically scans the Web for new sites and catalogues them; such software is often referred to as "crawler," "spider," or "bot" (short for "robot") software. Many indexes use a combination of the two methods, and some indexes catalog other portions of the Net in addition to the Web (an index called DejaNews, for example, catalogs messages in USENET newsgroups).

Where Are the Web Indexes?

In your searches, you will probably want to use various Web indexes, as they vary in both their content and the way in which they process search queries.

The following are the addresses for a few of the more popular Web indexes:

Using Your Browser Tools to Navigate the Web

Yet another method of navigating the Web involves using your browser's own controls. Most browsers "memorize" or cache the pages that you've accessed during a Web session, and have BACK and FORWARD buttons that let you go back and forth among these pages. Browsers may also have a GO menu that lets you hop back and forth between memorized pages out of sequence.

source:http://www.centerspan.org/tutorial/surf.htm
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