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Lecture 14 Internet and World Wide Web. Internet ( Inter Net work). Network Comprising of Numerous Worldwide Networks Largest Network in the World Connects Commercial, Academic and Government Networks Cannot Estimate the Number of Computers Comprising the Internet

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Lecture 14



World Wide Web

Internet (Inter Network)

Network Comprising of Numerous Worldwide Networks

Largest Network in the World

Connects Commercial, Academic and Government Networks

Cannot Estimate the Number of Computers Comprising the Internet

Attempt to “Map” the Internet Would Be a Futile Endeavor

Attempts Have Been Made


  • Predecessor of the Internet

  • Created in 1969 (mid 1960s)

  • Advanced Research Projects Agency

  • Designed to Ensure the Government's Ability to Continue Communicating in the Event of a Nuclear Attack

  • Initially Connected Four Supercomputers

  • Evolved into Today’s Internet

Internet Community

  • Users

  • People Who Use the Internet

  • Internet Service Providers (ISPs)

    • Provide Users Access to the Internet Resources Typically for a Fee

    • Includes Most Communication and Media Companies

Internet Content

Anyone Can Add Content to the Internet

No One Person or Organization Owns the Internet

Application Service Providers and Web Services Provide Resources


  • Protocol

    • Set of Rules for a Particular Situation

    • Communications Protocol

      • Rules that Determine How Devices on a Network Communicate

      • Computer Devices Cannot Transfer Data without Applying the Same Protocol

TCP/IP Protocol

  • Widely Used Communications Protocol

  • Built into Most Operating Systems

  • Used to Identify Computers and Devices on Networks

  • Consists of Two Protocols

    • Transmission Control Protocols (TCP)

      • Responsible for Delivery of Data

    • Internet Protocols (IP)

      • Addressing and Routing Information

Transmission Control Protocol

  • Rules for Transmitting and Receiving Data Packets Over the Internet

  • TCP Sets the Size of the Data Packets

  • TCP on Server Computer Breaks Web Page Data into Data Packets, Numbers the Packets, and Sends Data Packet

  • TCP on Client Computer Reassembles the Data Packets in the Correct Order

Internet Protocol

  • Rules Governing the Method by which Data Packets Are Transmitted

  • Most Important Function Is Uniquely Identifying Each Computer (Host)

  • A Host Is Identified by a 32-bit IP Address

  • Every Computer Connected to the Internet Must Have an Unique IP Address

IP Address

IP Addresses Are Expressed as Four Decimal Numbers


Each IP Address Has Two Parts:

Identifier of a Particular Network on the Internet

Identifier of the Particular Device within that Network

Transferring Data Example

  • Data Packet Is Sent from Transmitting Computer to a Gateway Computer

  • Gateway Computer Reads IP Address, Forwards to Another Gateway Node

    • Known as Routers

  • When Destination Gateway Recognizes the IP Address, Data Packet Is Forwarded to the Device within the Network Domain

  • Internet Related Protocols

    • For Displaying Web Pages

    • HTTP: Hypertext Transfer Protocol

    • HTTPS: HTTP Secure

    • For Transferring Files Over the Internet

    • FTP: File Transfer Protocol

    • For Delivering E-mail Over the Internet

    • SMTP: Simple Mail Transfer Protocol

    • POP3: Post Office Protocol 3

    • IMAP: Internet Message Access Protocol

    The World Wide Web

    • Collection of Web Pages on the Internet

      • Proposed by Tim Berners-Lee (1989)

      • Originally Text-based Content

      • Graphical Content with Mosaic (1993)

      • Based Upon Hypertext Markup Language

      • HTML and HTTP

    The Web

    Convenient and User-friendly

    Users Do Not Need to Be Experts

    The Fastest Growing Component of the Internet

    Internet Protocols Are Web Accessible

    Java, JavaScript, Visual Basic, XML

    The WWW Is a Dynamic Environment

    Stretching the Functions of the Internet

    Search Engines

    • Popular Function on the World Wide Web

    • Specialized Applications which Provide Three Main Applications or Functions

    • A Spider Application Searches and Identifies Internet Web Pages

    • A Catalog Application Creates an Index of the Spider's Search

    • A User Interface Compares a Request with the Catalog Providing Results

    Electronic Mail

    Transfer of ASCII Text Messages between Computers or Devices

    Messages Are Received on an Internet Server and Not to User’s Computer

    Most E-mail Applications Use SMTP

    POP3 Is Designed as a Store and Forward Application

    IMAP Is Designed as a Remote File Server

    Other Web-Based Services

    • Instant Messaging (IM) and Chat (IRC)

    • Message Boards

    • Voice Over Internet Protocol (VOIP)

  • Web Conferences and Webinars

  • Online Shopping

  • Online Banking and Investing

  • Online Entertainment

  • Online News

  • Web 2.0

    • Enhanced Version of the WWW

    • Social Networking

    • Twitter

    • Blogs

    • RSS (Really Simple Syndication)

    • Podcasts

    • Wikis

    Internet and WWW Issues

    • Censorship

      • Countries Blocking Internet Content

        • Hinders Spread of Information from Political Opposition

      • Internet Filtering

        • Using Software or Browser Options to Block Access to Particular Web Pages or Types of Web Pages

    Internet and WWW Issues

    • Spyware

      • Software that Transmits Data Secretly without Users’ Knowledge

      • Adware

      • Onscreen Advertising Software

      • Often Included in Free Programs

      • Does Not Gather Information

      • Is Installed without User’s Consent

    Internet and WWW Issues

    • E-mail Privacy

      • Employers’ Access to E-mail Messages

      • Only Encrypted E-mail Can Be Transmitted Privately

    • Web Browsing Privacy

      • Information About an Individual’s Web Browsing, How Used, and by Whom

      • Often Retained in Cookies

    Internet and WWW Issues

    • Social Networking

      • Users Should Be Careful Not to Reveal too Much About Themselves

      • Sites Monitored by Employers

        • Carefully Check What Is Posted

        • Remove Anything that Might Be Potentially Embarrassing

    Myths About the Internet

    Myth 1

    The Internet is Free

    Myth 2

    Someone Controls the Internet

    Myth 3

    The Internet and the World Wide Web Are One and the Same

    Lecture 14



    World Wide Web