intro computers

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill Technology EducationMcGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. All

rights reserved.


McGraw-Hill Technology Education

Chapter 2A

The Internet and the World Wide Web

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The Internet’s History• 1965- ARPA project

– ARPA of the US department of defense started a project in 1965

– Purpose was to connected universities and defense bases with each other

The Internet’s History• 1969 ARPANET

– The network established in 1969 and was named ARPANET

– Initially was consisting of only four (04) host computers

• ARPANET 1973– Extended to the whole Europe

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ARPANET 1973

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The Internet’s History• 1980-National Science Foundation (NSF)

– Joined the project in 1980 when Department of Defense stopped funding

• Mid-1980s – NSFNet– Network between 5 supercomputers centers for

academic and research purpose– Initially they used ARPANET for connection but the

existing ARPANET was unable to handle that much load and thus they started their own network NSFNet

– No commercial traffic allowed by NSFNet

The Internet’s History• Internet

– The link between ARPANET, NSFNet and other networks was called Internet

– Definition:• The global network of networks is called Internet

• Internetworking– The process of connecting different

networks

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The Internet’s History

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The Internet’s History

• 1990s– ARPANET shut down in 1990– NSFNet funding was disconnected in

1995– Commercial networks take over

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Today and the Future• 100,000 new web sites per month• More than 50% of U.S. households

online• Access is available throughout the U.S.• Eventually access will be global

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U.S. Internet Growth

The Internet’s Major Services• The World Wide Web (WWW)• Next chapter

– Electronic mail (e-mail)– News– File Transfer Protocol (FTP)– Chat– Instant messaging– Online services– Peer-to-peer services

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Understanding the World Wide Web

• World Wide Web– Also called Web or WWW

• Started in1989-– At European Particle Physics Laboratory in

Geneva, Switzerland• Purpose

– To create a simple way to access any document that are stored on a network


• 1993 -Tim-Berners Lee – In 1993 Tim-Berners Lee gave the idea to

linked documents stored on different computers across the world (on different networks) or on different computers on a network

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How the web works• The working of web need:

– Hypertext document• Collection of text files, pictures, sounds, movies

– HTML language• A markup language used to create hypertext documents

(called Web Page)• These documents are linked through hypertext links (also

called hyperlinks)• Web site are formed

– A collection of interrelated web pages is called Web Site

– Hypertext transfer protocol (HTTP)• To support web pages

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How the web works• Publishing a web page

– Uploading a wed page on server is called publishing a page

– Also called posting a page

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Web Browsers• A software application design to find a

hypertext document (Web page) and then open the Web page on the user computer

• Examples:– Internet Explorer– Mozilla Firefox– Google Chrome– etc.

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Uniform Resource Locator (URL)• An Internet address of a web page is

called URL– Format:

• Type:\\address\path– Type: specify type of the server: web server or file

server– Address: address of the server– Path: location within the file structure of the server

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• Wed document in URL

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Wed Wed DocumentDocument

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Understanding The Internet• Helper applications and multimedia

contents– Limitation of web-browsers:

• Browsers individually cannot display every type of contents (video, audio, animations)

– Solutions to the problem• Plug-ins are the special application softwares

that are used to play the contents in real.• Enhance a browser’s functionality• Used for Streaming audio and video• Sends the file in small chunks• Chunks downloaded while others play

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Streaming Audio

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Using a Browser And The WWW• Start the browser• Enter the URL

– Three methods are used for entering URL

• The home page of the web site will load in browser window

• Use hyperlinks to navigate through the website• When finished, close the browser

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Searching the Web• The Web is unorganized collection of

billions of documents from different sources

• It is too difficult to get honest, trusty and accurate information from the web easily

• To solve this problem:– Search engines: are used

Searching the Web• Types of search engines:

– Directories-based• Categorize the documents into subjects i.e.

educationschoolsubjectcomputer• Example:

– www.looksmart.com/

– Keyword based• Find sites by keyword

– www.google.com

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Searching the Web• Problems in search engines

– Sponsored links• The links (web sites) for which the owner pays to the

search engines owners for displaying their links at the top of the links in the search engines windows

– Irrelevant documents are retrieved• Solutions to the problems

– Website-specific searching tool• www.microsoft.com, www.cnn.com

– Advanced search: uses form having filters• www.google.com, www.yahoo.com

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Searching the Web• Metasearch sites

– A metasearch engine is a search tool that sends user requests to several other search engines and/or databases and aggregates the results into a single list or displays them according to their source.

• www.mamma.com

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Search Techniques• Quote the exact phrase• Boolean operators in search• Use the keyword NEAR• Avoid common words

– Is, or, no etc.• Use the site’s advanced tools

– www.google.com– www.yahoo.com

• See next slide

Search Techniques• Logical operators: AND, OR, NOT

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McGraw-Hill Technology Education

Chapter 2A

End of Chapter