The Internet

The Internet as a Phenomenon

• The Internet is a loosely configured, rapidly growing labyrinth of networks,

composed of computers from around the world,
owned by multiple corporations, organizations, and individuals.


Don't Know Much about History
 

• The Internet existed for approximately 25 years before the general public even knew about it.
• It was started by the military as a vehicle for their own purposes; they never imagine that it would become the international giant it is today.


First Stirrings at the Department of Defense
 

• In the 1950's Cold War, the United States Department of Defense, concerned that a single bomb could wipe out their computing capabilities, decided to rely on several computers, geographically dispersed.
• A message sent to another computer is divided into packets, each packet labeled with its destination address and winding its way individually through the network.  The message is eventually reconstituted at the end of the journey.  Thus, if one computer was knocked out the others could still carry on, by using alternative routes.
• The software that takes of the packets is Transmission Control Protocol/Internet Protocol(TCP/IP); TCP does the packeting and reassembling of the message and IP handles the addressing, seeing to it that packets are routed across multiple computers.
• The set of connections was called the Advanced Research Projects Agency Network (ARPANet).(The year was 1969.)
• In 1990, Dr. Tim Berners-Lee, a physicist at CERN, knew his work would be easier if he linked his and his colleagues’ computers together on a network.  He saw the linked machines as a spider’s web, hence the term “Web”.  The author of the Web was Tim Berners-Lee.
• A link on a Web site is easy to see: it is colored text, called hypertext or an icon or image, called a hyperregion.
• Marc Andreessen was a student when, in 1993, he led a team that invented the browser, software used to explore the Internet.
• The browser, Mosaic, featured a graphical interface, so that users could see and click on pictures as well as text.  Today, several competitive browsers exist, such as Netscape and Internet Explorer.


The Internet Success Factors

 
The emergence of the Internet is due to four factors:
 
1. The universal TCP/IP standard
2. The web-like ability to link from site to site
3. The ease of use provided by the browser’s graphical interface
4. The growth of personal computers and their LANs connected to the Internet


Getting Started

The following sections briefly cover the process of accessing and using the Internet and its resources.


The Internet Service Provider and the Browser

An Internet user needs:
• A computer with a modem and its related software,
• An Internet service provider (ISP).
• A browser .
An Internet service provider (ISP) provides the server computer and software to connect to the Internet.
A brower is the software on the user's computer to access the Internet via the service provider, using a graphical interface.

You can also sign up for an online service to access the Internet
Approximately two thirds of Internet users connect via online services.  The other third use ISPs.
To use an ISP, you must first decide which one.
    Once you have arranged to pay the fees (installation, monthly), you’ll set up your ISP as the provider’s instructions direct.
The next step is to install the browser software.
    You can purchase a browser in your local software retail outlet. You could download a browser for free.
Once set up, you invoke the browser like any other program.


    The Browser in Action

Two popular browsers are Marc Andreesen’s Netscape Communicator and Microsoft’s Internet Explorer.
When you start the browser, it will dial up the ISP and, once connected, display either the home page of the Web site that created your browser or
some other site designated by the ISP.

    The Parts of a Browser

• Browser control panel - shows the web address currently displayed, buttons to go to the previous/successive pages visited.
• Browser display window - the largest part of the display. Shows the content of the current web page.
• Browser status line - shows the status of data being loaded or the destination of selected links


    Browser Functions and Features

The following sections cover the functions and workings of the browser control panel.
    Menus and Buttons
Using a mouse you issue commands through a series of menus, a set of choices typically selectable from the top of the screen.
    Most menus are pull-down menus, at the very top of the display.
Buttons also invoke commands.
    Back and Forward traverse site history, Print prints a web site, Home goes to the home page.
    URL
The location slot contains a rather messy bit of text called the Uniform Resource Locator (URL).
(URL is a string of letters and symbols locates a web page on the Internet.)
• First, the HyperText Transfer Protocol (http://)
• Second, the domain name, the address of the ISP contacted.

(If it is a commercial site, it ends in .com, .org means nonprofit organization). (http://www.kevinmitnick.com)
• Third, the paths, directories, and file names of sites and their content loaded by the browser.
• Understanding and Using URLs from Memphis City School.
• A useful web site to be visited
    Java
Java is a programming language developed by Sun Microsystems, used to write software that can run on any machine.
Java makes possible the dancing icons, sound clips, flashing messages, and scrolling banners that you see on the Internet today.
The Java programs that provide multimedia effects are called applets.
    Moving from Site to Site
Most browsers provide lists of clickable categories.
Many home sites provide “cool” links to selected pages.
If you want to be specific, you can delete the URL listed in the location  bar and enter a desired URL to “transport” you to an intended site.
Searching the Internet
A search engine is software, usually located at its own web site, that lets a user specify terms; the search engine then finds sites that fit those terms.
A search engine finds sites by building a database, following links across the Web and keeping data on some or all of the words on a Web site.
          Search Engine Limitations
Search engines are known for turning up too much information.
But even with the pages they turn up, search engines only search about one third of the entire Web.
For now, the best way to turn up Web pages with content you want is to use multiple search engines.
        Whether or not a file is available for downloading depends on two things:
(1) whether you are allowed to download files to the hard disk of the computer you are using
(2) whether the file you want is available for copying
All kinds of files - programs, text, graphics, images, even sounds - are available to be copied without restriction.
Home Page
          It is a first page of a web-site.
Boolean Operators
          It will give a result of true or false.
          for example,
•           OR -    You have an apple OR You have a banana.
•           AND -  You have an apple AND You have a banana.
•           NOT -   You are NOT a student.
•           IN -  This is not a Boolean Operator.