Lesson 2 — The Internet and the World Wide Web

Unit 1 — Computer Basics

Lesson 2 — The Internet and the World Wide Web2

Objectives

Describe the origin of the Internet. Describe how the Internet works. Describe the major features of the Internet. Explain the difference between the World

Wide Web and the Internet.

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Objectives (continued)

Explain how to connect to the Internet. Describe a browser. Understand browser terminology. Understand and use browser features.

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Evolution of the Internet

The Internet is a worldwide network of smaller networks. The Internet evolved from the ARPANET. The ARPANET was the first large-scale network,

created around 1969.– It was developed as a government research project.

The World Wide Web (WWW) was born in 1992.– This spurred more growth of the Internet.

The first Web browser, Mosaic, was released in 1993.– This triggered an explosion in Internet use and growth.

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How Does the Internet Work?

Internet computers talk with each other in a manner similar to mailing a letter to some one: by sending it to an address.

Internet computers all have a unique address. Computers communicate using TCP/IP protocol.

– This is the international standard for exchanging data.– TCP establishes a connection between two host computers.– The IP protocol allows you to enter an address of a computer

and send something to that address.– You can enter an address as a domain name.

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Example of Internet Communication

This figure shows a very simplified version of how the Internet works. One computer mails a letter to another computer, and the TCP/IP protocol handles the addressing between the two machines.

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Major Features of the Internet

The Internet is made up of many services, including– The World Wide Web (WWW)– E-mail– Chat rooms– Mailing lists– FTP sites– Newsgroups

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The World Wide Web

The WWW is NOT the Internet.– It is an application that uses the Internet.

It consists of millions of electronic files called Web pages. A related collection of Web pages is a Web site. Web sites can be created by businesses, organizations,

and individuals. Web pages frequently contain hyperlinks.

– A hyperlink can transport you to another page or site just by clicking on the hyperlink.

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Web Protocols - HTTP

HTTP is a protocol that defines how messages are formatted and transmitted.

Web pages are sent in HTTP protocol.– Web servers and Web browsers both can understand HTTP.

Every Web site has a unique address called an URL.– The first part of an URL indicates the protocol required to

access the page.– The second part of an URL specifies the IP address or a

domain name.– The top-level domain at the end of the URL indicates the type

of organization or business.

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An URL and Its Web Site

This figure shows the Hamster Dance Web site in a browser window. The URL is shown in the Address Bar of the Web browser, and that address is what the user entered in the browser to arrive at this site.

HTTP://www.hamsterdance.com

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Web Protocols - HTML

HTML is a protocol that determines how a Web page is formatted.

Web pages consist of text coded with HTML markup tags. The Web browser reads the tags and formats and displays the

page.– Different browsers may interpret certain HTML tags differently.

Factors that affect how a page displays include– The type and version of browser being used.– The actual HTML tags being used.– The type and resolution of the monitor being used.

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Accessing the Internet

There are a variety of ways to connect to the Internet, including– Through a modem and telephone line.– Through a local area network.

This requires a network interface card (NIC) in your computer.

– Through high-speed leased lines.

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Use a Modem and Phone Line to Access the Internet

If your computer has a modem installed and a phone line connected to it, you can access the Internet by

– Locating and signing up with an ISP. An ISP is an Internet Service Provider.

– Installing telecommunications software on your computer.– Installing a Web browser on your computer.– Setting up your modem to dial a telephone number supplied

by your ISP.– Having the modem dial out and log in to your ISP. You are

now on the Internet.

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Access the Internet via a Network

This figure shows how the Internet can be accessed via a LAN. The computers on the LAN are able to get to the Internet through a high-speed line connected to the LAN, which is also connected to the Internet.

LAN

High-speed line

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Other Internet Connections

DSL: Digital subscriber lines– Very high-speed connection over standard phone lines

Cable modem– Very high-speed access, usually using cable television

lines WebTV

– Uses hardware that connects to your television and a standard phone line

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What Is a Browser?

A browser is a software program that you use to retrieve information from the World Wide Web and display it in readable format.

A browser can display text, images, sound, animation, and video.

You navigate the Web by using your mouse to point to and click on hyperlinked words and images displayed in your browser.

The two most popular browsers are Microsoft Internet Explorer and Netscape Navigator.

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Summary

No one person or organization can claim credit for the Internet.

Origins of the Internet can be traced to the U.S. Department of Defense. The original name for the Internet was ARPANET.

Mosaic was the Internet’s first graphical interface, or browser.

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Summary (continued)

To connect to the Internet from a business or academic setting, you probably have a direct connection via a local area network and a network interface card. For the home user, the most common type of Internet connection is with a modem and telephone line.

To connect to the Internet, you need an Internet connection, telecommunications software, and a browser.

Other types of Internet connections include ISDN, DSL, cable modem, and WebTV.

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Summary (continued)

Interoperability means that all brands, models, and makes of computers can communicate with each other.

A protocol is a standard format for transferring data between two devices. TCP/IP is the agreed-on international standard for transmitting data.

The domain name identifies a site on the Internet.

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Summary (continued)

The Web is an application that makes use of the Internet. Other features of the Internet include electronic mail, chat rooms, mailing lists, and newsgroups.

Web pages can be linked through hypertext. Microsoft Internet Explorer and Netscape

Navigator are two of the most popular Web browsers.

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Summary (continued)

The HTTP protocol defines how Web messages are formatted and transmitted.

The Web site address is referred to as the URL, or Uniform Resource Locator. Every Web page on the Internet has its own unique address.

A Web page is coded with HTML markup tags. HTML is another protocol that controls how Web pages are formatted and displayed.