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What is the Internet?

What is the Internet?. S F ICTD 111. What is the Internet?. It is a vast network of networks. On the Internet, you can . . . Find information about anything Communicate with people worldwide Search the world’s libraries Visit famous museums Take an online course

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What is the Internet?

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  1. What is the Internet? S F ICTD 111

  2. What is the Internet? It is a vast network of networks

  3. On the Internet, you can . . . • Find information about anything • Communicate with people worldwide • Search the world’s libraries • Visit famous museums • Take an online course • Watch videos and television • Listen to music and the radio • Read magazines and newspapers • Shop for almost anything

  4. The Internet includes . . . • World Wide Web – multimedia content • Email – send and receive messages • Instant messaging – communicate in real time with a connected user • Chat – participate in a group conversation in real time • FTP (file transfer protocol) – upload or download files on another computer

  5. Who runs the Internet? • No single group or organization runs the Internet; it is a collaborative entity • Individual networks belong to universities, corporations, research groups, government agencies, and large service providers like America Online • New networks are added every day • Your computer is one node on the Internet

  6. How does the Internet work? • The networks communicate with each other based on certain protocols (or standards), such as TCP/IP • TCP = Transmission Control Protocol • IP = Internet Protocol • The individual local networks cooperate to direct Internet traffic so information can pass among them.

  7. How is data transferred between computers on the network? • Telephone lines with a dialup modem* (slow) • Cable TV lines with a cable modem (fast) • DSL: Digital Subscriber Lines (fast) • Dedicated T1 or T3 lines (fast) * = Modulator-Demodulator

  8. How is data transferred between computers on the network? Con’t • Local area wireless networks • Fiber optic cables • Satellites • and many other ways . . .

  9. Modem Device connecting computers via phone line: An electronic device that connects computers via a telephone line, allowing the exchange of information. It consists of a modulator to convert computer information into a telephone signal and a demodulator to convert it back again.

  10. A typical dial-up modem connection phone line to another network phone company network computer modem

  11. A typical cable modem connection with a wireless hub cable television wireless laptop cable splitter to a regional network wireless hub cable company computer cable modem

  12. For example, in UEW computer lab (see next slide) • Each computer is connected to the lab’s server • The lab server is connected via fiber optic cable to the main South Campus server in the administration block • The South Campus server is connected via radio signals to the Internet server on the North Campus five miles away. • The Internet server sends and receives information via the university’s satellite to AfroNet, an ISP in the capital city, which sends and receives worldwide via satellite.

  13. Lab connection for a university in Ghana satellite to a regional network South Campus South Campus main server North Campus web server computer lab LAN file server

  14. How data travels on the Internet • Data is broken into small packets • Each packet has a header that tells its destination and its order • Routers send packets individually using the most efficient path • When all the packets are received at the destination, they are reassembled in their original form

  15. How data travels over the Internet To: From: To: From:

  16. The World Wide Web • World Wide Web = W W W = web • The web is a subset of the Internet, but the terms are often used synonymously • The web is a collection of web pages • Each page usually has multimedia content • Pages are connected to each other via hyperlinks • Anyone can add a page to the web

  17. How the web works • Web pages are written using HTML • (hypertext markup language) • The pages are uploaded to a web server • (a computer configured to locate and send web pages) • You view the web page using a browser • (software like Internet Explorer or Netscape Navigator) • The term home page refers to the introductory page in a collection of pages. The collection of pages is called the web site.

  18. Steps to create your own web page • Design the content and layout in web authoring software (such as FrontPage). • The software converts it to HTML code. • Use FTP software to upload the page and the images to a web server where you have been given access. Note the address (URL) where your page is stored. • Then anyone can view your page in a browser (such as Internet Explorer) by typing in your page’s address (URL).

  19. Web addresses* http://schooldiscovery.com/schrockguide/index.htm • http:// is the protocol for transferring web pages • schooldiscovery.com is the domain name (it identifies the computer where the web page is stored; it usually begins with www.) • schrockguide is the name of the folder • index.htm is the name of the file *Also called a URL = Uniform Resource Locator

  20. Web addresses (URL’s) http://oak.cats.ohiou.edu/~turners/index.htm • http:// is the protocol for transferring web pages • oak.cats.ohiou.edu is the domain name (it identifies the computer where the web page is stored; it usually begins with www.) • ~turners is the name of the folder • index.htm is the name of the file

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