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Computers Are Your Future

Š 2008 Prentice-Hall, Inc.


Computers Are Your Future Chapter 2

Computers Are Your Future

Chapter 2 The Internet & World Wide Web Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

What You Will Learn . . .  How the Internet works  Methods for accessing the Internet  The Internet and the World Wide Web  Hypertext  Web browsers and Web servers

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

What You Will Learn . . .  Parts of a URL  How to access Web pages  Web subject guides and search engines  Use operators to improve search results  Reliability of information on the Web  Most popular Internet services

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

The Internet  Interconnected network of computer networks  Global The Internet is a global, interconnected computer network in which every computer connected to it can exchange data with any other connected computer. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Computer Network ďƒ˜ Network -- two or more computers connected together for the purpose of communicating and sharing resources

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

How the Internet Works Interoperability is the ability to communicate with a computer even if it is a different brand or model.

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Accessing the Internet and Web

You will need:  A computer with an operating system, such as Windows, MAC OS, or UNIX, that supports Internet protocols  Communications equipment such as a modem, ISDN adapter, or Ethernet card  An Internet service provider (ISP)  Web browser software such as Internet Explorer or Netscape Navigator © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Accessing the Internet The Internet can be accessed in the following ways:  Dial-up access with Point-to-Point Protocol (PPP)  Digital Subscriber Line (DSL)  Cable and satellite access  LAN access

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

The Internet and Web: What’s the Difference?  The Internet is the physical connection of millions of networks.  The Web uses the Internet for its existence.  The Web consists of hypertext embedded on Web pages that are hosted on Web sites.

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

The Web Site  A Web site is a collection of related Web documents that are made available to the public.  The index page, or home page, is the first page of a Web site.  Web pages are individual Web documents.

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

The Hypertext Concept  Hypertext is a way of presenting information so that the order in which it’s read is left up to the reader.  Hyperlinks are underlined or highlighted words that can be used to view another document or Web page.  Hypermedia refers to a link to multimedia, such as music and movies.  The Web is a distributed hypermedia system or a system where the responsibility for creating content is distributed among many people. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Client/Server Model  Client/Server can describe a relationship between two computer programs – the "client" and the "server".  Client  Requests some type of service (such as a file or database access) from the server.

 Server  Fulfills the request and transmits the results to the client over a network © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Example of Client/Server Model  Client -- Web Browser  Server -- Web Server

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Web Browsers and Servers

 Web browsers display a Web document and enable users to link to other Web pages. • The first browsers were text-only. • Mosaic was the first graphical browser.

 Web servers respond to the requests of browsers. They find and send requested resources back to the browser. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Mosaic 1.0

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Web Addresses (URLs)  Web addresses are an addressing system that identifies where a Web resource is located.  The uniform resource locator (URL) is the standard used to identify Web resources.  The URL consists of: Protocol identifies the means of access.

Server contains the domain name of the Web server.

Path identifies the location of the document.

Resource specifies the filename of the resource.

URL http://www.yahoo.com/ help/shop/ shop-01.html

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

What’s a protocol? human protocols:

network protocols:

 “what’s the time?”  “I have a question”  introductions

 machines rather than humans  all communication activity in Internet governed by protocols

… specific msgs sent … specific actions taken when msgs received, or other events If people run different protocols  cannot operate & no useful work

protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

What’s a protocol? a human protocol and a computer network protocol: Hi

TCP connection req

Hi

TCP connection response

Got the time?

Get http://www.awl.com/kurose-ross

2:00

time

<file>

Q: Other human protocols? Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Domain Name System

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Computers Are Your Future Chapter 2

Browsing the Web To access a Web page, you can do any of the following:  Click a hyperlink  Type a URL in the Address box  Click a button on the Links toolbar  Use the Back and Forward buttons  Use a Web site’s navigation aids  Use the History list  Use the Favorites or Bookmarks list

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

The Web Browser’s Window

History Button– List of Printer Button– Prints Standard Toolbar– Web sites visited over a Back & Forward Media Buttons– Button– Opens documents Favorites Button– List Contains Navigation buttons Refresh Search Button– Button– Opens period of time Stop Button– Take you to recently media player visited program Home Button– Returns of bookmarked Web Updates search engine (refreshes) program the Stops downloading pages to default start page pages E-Mail Button– Opens page

Program icon– Other Navigation Buttons Animates when Address Bar– downloading Contains URL of Web page

e-mail program Hyperlinks

Status bar– Messages about the browser’s operation

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Growth of Internet  Hobbes Internet Timeline  http://www.zakon.org/robert/internet/timeline/ Year 1969 1989 1992 1995 2001 2002 2003 2006 2009

© 2008 Prentice-Hall, Inc.

Host Computers 4 100,000 1,000,000 8,000,000 109,000,000 147,000,000 171,600,000 439,000,000 700,000,000

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Computers Are Your Future Chapter 2

Reasons for Internet Growth in the 1990s  Removal of the ban on commercial activity

 Development of the World Wide Web by Tim Berners-Lee at CERN  1990

 Development of Mosaic, the first graphics-based web browser at NCSA  1992-1997 © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Uploading and Downloading  Downloading – document or file is transferred from another computer to your computer  Uploading – files transferred from your computer to another computer

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Emerging Technologies Ways to share information on the Internet  Wiki – open-content encyclopedia  Weblog (blog) – Internet journal or diary  Moblog (mobile blog) - content posted from a portable phone or PDA

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Finding Information on the Web Ways to find information on the Web:  Browse or surf the Web – This involves linking from one Web page to another, and so forth.  Search the Web – This method involves using search engines to locate Web pages with the information you’re looking for.  Subject guides – Web pages are grouped under headings. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Using Search Engines  To use a search engine, you: • Choose a search engine (MSN, Lycos, Alta-Vista, Yahoo, etc.). • Type in one or more words describing your topic.

 The search engine checks its database of Web pages that contain the words typed  The results are sent to your computer.  Clicking on the link takes you to the corresponding page.

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Search Engines ď&#x192;ź When you are using a search engine, you are NOT searching the entire web as it exists at this moment. You are actually searching a portion of the web, captured in a fixed index created at an earlier date.

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Using Search Techniques  Learning a few search techniques can increase the accuracy of Web searches.  Searches using search operators will improve search performance.  Most search engines use the following search operators: • • • •

Inclusion/exclusion operators Wild cards Phrases Boolean operators

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Using Search Techniques The following tables show the results of using and not using search operators. Using Search Operators No Search Operators Words Entered

Possible Results – Web pages containing Fire station Fire station Fire station

Words Entered +Fire+station

Possible Results – Web pages containing Fire station

+Fire-station*

Fire station Fire stations Fire

“Fire station”

Fire station

+Fire+station*

Fire and station Fire station Fire or station Fire not station © 2008 Prentice-Hall, Inc.

Fire station Fire station Fire Slide 32


Computers Are Your Future Chapter 2

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

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Computers Are Your Future Chapter 2

Rules for Evaluating Web Pages 1. 2. 3. 4. 5. 6. 7. 8.

Author – Who is the author? Sources – Where does the information come from? Server – Who provides the server for the page? Objectivity – Is the information objective or one-sided? Style – Is the language objective or argumentative? Purpose – What is the purpose of the page? Accuracy – Is the information accurate? Currency – Is the page up-to-date?

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Using the Web for Schoolwork  Use authoritative online sources.  Use your library to find articles and books.  Cite online and offline references.

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Search Engine and Your Career  Work in group  Do you think your future job requires to use search engine?  If so, come up with an example that is specific to your major  For ex  A programmer uses the search engines to find references to a programming language

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

E-Mail: Staying in Touch

 E-mail is short for electronic mail.  It’s the most popular of the Internet services.  Messages are sent and received in a few seconds.  Attachments such as photos, music files, and any document may be sent with the message. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

E-Mail Addresses

 myname@someserver.com  User’s name@name of the server that the user is on

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Spam: Can It Be Stopped? Spam – unsolicited e-mail advertising  With Spam the recipient pays the postage.  To avoid spam:  Avoid posting your e-mail address.  Use spam protectors.  Don’t reply to spam.

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Instant Messaging: E-Mailing Made Faster

 Instant messaging systems let a user know when a friend or business associate is online.  It provides a means of communicating through real-time, text-based conversations. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

IRC: Text Chatting in Real Time

 Internet relay chat consists of real-time, text-based conversations.  Chat groups are divided into channels that cover a specific topic. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

File Transfer Protocol (FTP) Your Computer

FTP Server DOWNLOAD

UPLOAD

 FTP is a part of the Internet that enables client computers to transfer files.  Transferring files from an FTP site to the client is known as downloading.  Transferring files from the client to an FTP site is known as uploading.  Clients may store files on an FTP site’s server. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Usenet  Usenet is the part of the Internet which enables users to participate in discussions and newsgroups.  Usenet newsgroups are organized into hierarchies (categories) and subcategories.  Subcategories include Standard, Alt, Biz, and Local newsgroups. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Standard Newsgroup Subcategories comp

computer applications, databases, multimedia

misc

activism, books, business, health

sci

chemistry, archeology, math

soc

human rights, world cultures

talk

Euthanasia, gun control, religion

news

Usenet announcements

rec

sports, gardening, bicycles

Š 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Listservs: Electronic Mail Lists  A listserv is an automatic list server.  Mail is sent to everyone on the list when e-mail is generated.  It is similar to a newsgroup or a forum.

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Personal Web Site vs Blog  Which one do you prefer? Why?

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Chapter 2 Summary

 The Internet is the interconnected network of computer networks.  The Internet is accessed by way of an ISP.  World Wide Web is a global system with billions of hypertext documents.  Related information is linked using hypertext.

© 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Chapter 2 Summary (continued)

 A Web browser is a program that displays Web pages.  A URL consists of a protocol, a server, a path, and a resource name.  Search engines enable you to search huge databases of Web documents.  You can improve search results using operators. © 2008 Prentice-Hall, Inc.

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Computers Are Your Future Chapter 2

Chapter 2 Summary (continued)

 You should always evaluate information you receive from the Web  Popular Internet services include: • E-mail • Instant messaging • Internet Relay Chat • File Transfer Protocol • Discussion groups • Listservs © 2008 Prentice-Hall, Inc.

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Chapter 02  

Chapter 02

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