Internet and Web Concepts - PowerPoint PPT Presentation

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Internet and Web Concepts What is a URL? The Internet and the World Wide Web (subset) What is a browser? HTTP is? means… What is “hypertext?” What do we mean by client-server? Server Client HTTP Home Page Browser LAN Modem ISP KEY CONCEPTS

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Internet and Web Concepts

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Internet and Web Concepts

  • What is a URL?

  • The Internet and the World Wide Web (subset)

  • What is a browser?

  • HTTP is?

  • means…

  • What is “hypertext?”

  • What do we mean by client-server?

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Home Page






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Connecting to the Internet

ISP (Internet Service Provider)—connects to the Internet, and the user pays the hook-up fee and use charges. Examples: AOL, MSN, UIUC

  • Modem—Uses a phone line to reach a server

  • Cable — needs a cable modem (not really a modem!)

    Only if you have a T1 line do you have a direct connection to the Internet

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Other means of connecting

  • DSL (Digital Subscriber Line) — uses a DSL transceiver. You use your regular phone line, too.

  • ISDN connections use a special digital phone line that must be installed to your home by your local telephone company. They need a “Terminal Adapter”– also often called a “modem” (but it isn’t one)

  • Wireless Involves no wiring, just an antenna!

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Programs communicate, not computers

A program on one computer uses protocol software to contact a program on another computer– a protocol is an agreed format that computers on the Internet use to communicate.

  • E-mail protocols:

    • SMTP - Simple Mail Transfer Protocol

    • POP - Post Office Protocol

  • File transfer protocol: FTP

  • It is all based on…

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Transmission Control Protocol/ Internet Protocol

TCP/IP is an agreed format that computers on the Internet use to communicate. Any computer that understands TCP/IP can connect to the Internet. Involves packets.

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VOIP -- Internet Telephony

  • Make your phone calls over the Internet! Voice over Internet Protocol; using packet based networks instead of the standard telephones to send voice data

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Converting a voice to digits

  • Digital phones convert your voice into binary information (1s and 0s) and then compress the data

  • The person you talk to hears your voice after the 1s and 0s are changed back to sound

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  • Electronic messages are sent to your account and stored on a ___________________.

You send a message to someone. First it goes to a server

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  • Email software is later used to download messages from the __________ that is storing the message.

You receive email from the server, where it has been stored for you

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Client/________ Relationship

What is a server?

  • Some computers on the network offer services that others can access.

    • ftp server -- email

    • Yahoo, Google --

    • Library catalogues

Your query goes to the server

Server sends back information

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  • Systems like KaZaa

  • Files held on individual machines rather than centralized server

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Internet Addressing -IP Addresses

  • Computer ports, called servers, connected to the Internet have unique addresses.

IP number is a 32-bit address in four parts, of 8 bits each, and therefore, in 8 bits you can only represent the numbers 0 to 255 (256 possible numbers). Thus this address is not possible:

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Internet Addressing -Domain names

  • These 4-part numbers are converted into easy-to-remember domain names.,,



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  • HTTP -- HyperText Transfer Protocol

    The protocol used for a web document (HTML).


  • HTTPS:

    • A HTTP protocol that provides for more secure web communications by including encryption methods.

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Domain Naming System

  • provides mnemonic help in identifying sites

  • organizes the names of computers, subnetworks, and larger networks

  • reading left-to-right, information becomes more general

educational site

University of Illinois @ Urbana-Champaign

Computer Science Department

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http:// ....... specifies Hypertext Transfer Protocol,

/ ......... Identifies location of web server

~ means bypass intermediate directories and go straight to the directory named roberta (~ is called a tilde)

index.html ........ is the name of the home page and will appear whether or not you type index.html!


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Internet Addressing -URL Example






Top Level


Student or Employee

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Spam, Phishing – Where does this link take you?

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Internet Addressing -Top level domains

  • You can find out who owns a domain name.


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Top Level Domains

.comCommercial businesses

.orgNon-profit organizations

.netNetwork services

.govGovernment agencies

.eduEducational institutions



.nomFor individual users

.webWeb-based businesses


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Common Country Domains

  • .auAustralia

  • .fiFinland

  • .cn China

  • .ukUnited Kingdom

  • .usUnited States

  • .il Israel

  • .ch Switzerland

  • .mxMexico

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Country IDs

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Sample Email Address


Name of your ISP’s

host computer

Your userID

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Using ph to find a person’s email address


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  • HyperText Markup Language (HTML)

    A convention of codes used to display content such as words, pictures, etc. Without HTML code, a document would be unreadable by a Web browser. Right now, HTML is the Language of the World Wide Web, but the web is moving toXHTML

    Extensible Markup Language (XML) is the universal format for structured documents and data on the Web—it is compatible with XHTML but not with HTML. XML is built into the Windows XP operating system.

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