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Internet and cyberspace


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Lecture Slides of Introduction to Information Technology. The lecture slides are based on the book of Brian K. Williams and Stacey C. Sawyers

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Internet and cyberspace

  1. 1. Internet and Cyberspace Instructor: Ch. Bilal Ahmad Khan Company LOGO
  2. 2. History of Communication and Internet Slide Rule-1621 Mechanical Adding Machine -1642 Ada Lovelace - 1843 First Telephone - 1876 Telegraph Message Machine - 1844
  3. 3. History of Communication and Internet First Radio Broadcast -1907 First Radio Signal - 1895 First ATM - 1963
  4. 4. Internet Operation
  5. 5. Internet Operation
  6. 6. Applications of Internet
  7. 7. Data Transmission Capacity  Bandwidth, or channel capacity, is an expression of how much data - text, voice, video, and so on - can be sent through a communications channel in a given amount of time   The type of data transmission that allows only one signal at a time is called baseband transmission several signals can be transmitted at once, it’s called broadband transmission  Broadband - very high speed - connections  Fiber Optics, DSL, cable, and satellite and other wireless connections
  8. 8. Physical Connection for Internet  Wired     Dialup ISDN DSL T1  Wireless   Through Air Link (e.g. PTCL EVO, Wateen, Wi-Tribe) Satellite
  9. 9. Data Transmission Speed  bps   Bits per second Eight bits equals one character, such as A, 3, or # Kbps  Kbps   kilobits per second 1 thousand bits per second  Mbps   megabits per second 1 million bits per second  Gbps   gigabits per second 1 billion bits per second
  10. 10. Connecting with Internet  Narrowband  Dialup Connections  Connecting with Modem  Modems and Call Waiting Source: Using Information Technology by William and Sawyer
  11. 11. Connecting with Internet  High Speed Phone Lines    ISDN (Integrated Services Digital Network) consists of hardware and software that allow voice, video, and data to be communicated over traditional copper-wire telephone lines DSL (digital subscriber line) uses regular phone lines, a DSL modem, and special technology to transmit data in megabitsper second T1 line, essentially a traditional trunk line that carries 24 normal telephone circuits and has a transmission rate of 1.5 to 6 Mbps
  12. 12. Connecting the Internet Source: Using Information Technology by William and Sawyer
  13. 13. Wireless Connections  Satellite Communications  Communications satellite, a space station that transmits radio waves called microwaves from earth-based stations  Wi-fi  802.11 standards by IEEE of wireless transmissions  Transmission of data at up to 54 Mbps  300-500 feet covered by access point  2G  Used for mobile communications  3G  High-speed wireless technology that does not need access points because it uses the existing cell phone system
  14. 14. Working of Internet  Client   computer requesting data or services Normally a computer in front of user  Server   Is a central computer supplying data or services requested of it Also known as host computer
  15. 15. Working of Internet  Point of Presence  Local access point to the internet  A collection of modems and other equipment in a local area  POP acts as a local gateway to the ISP’s network  Network Access Point  A routing computer at a point on the internet where several connections come together  Owned by a network service provider  Internet Backbone  High-speed, high-capacity transmission lines that use the newest communications technology to transmit data across the internet
  16. 16. Working of Internet
  17. 17. Working of Internet  Protocols  Set of rules, that computers must follow to transmit data electronically  The protocol that enables all computers to use data transmitted on the internet is called Transmission Control Protocol/Internet Protocol, or TCP/IP,  Packets  TCP/IP breaks the data in a message into separate packets  Fixed-length blocks of data for transmission  IP Address  Internet Protocol (IP) address uniquely identifies every computer and device connected to the internet
  18. 18. World Wide Web  Design and Develop Web Site  Choose the name of website  Buy domain name with Web Host  Web Host provides web space  Upload files to the web server  Write the URL in the web browser  Browse the website Client Server Send Database Request Request Data Fetch Fetch Reply Data
  19. 19. World Wide Web  Design and Develop  Write the URL in the Database web browser  Design and Develop  Browse the website Web Site Server  Choose the name of Client Send Database website Request Request Data  Buy domain name SQL Query with Web Host Fetch Fetch Data  Web Host provides Reply web space  Upload files to the Data web server
  20. 20. World Wide Web  URL  URL (Uniform Resource Locator) is a string of characters that points to a specific piece of information anywhere on the web
  21. 21. World Wide Web  Protocol (http://)   HyperText Transfer Protocol (HTTP) , the communications rules that allow browsers to connect with web servers Another protocol is ftp://  Domain Name  Domain is simply a location on the internet, the particular web server  Directory Name  The directory name is the name on the server for the directory, or folder, from which your browser needs to pull the file  File Name  The file is the particular page or document that you are seeking
  22. 22. Search Engines  Search services are organizations that maintain databases accessible through websites to help you find information on the internet  Search engines are programs that enable you to ask questions or use keywords to help locate information on the web  Spiders - also known as crawlers, bots (for “robots”), or agents – that crawl through the World Wide Web, following links from one web page to another and indexing the words on that site
  23. 23. Search Engines  Individual Search Engines    Compiles its own searchable database on the web Hits are defined as the sites that a search engine returns after running a keyword search Examples are Bing, Yahoo, Google etc  Subject Directories   Created and maintained by human editors, not electronic spiders, and allows you to search for information by selecting lists of categories or topics Examples are Galaxy, Google Directory, LookSmart, Open Directory Project, and Yahoo! Directory
  24. 24. Search Engines  MetaSearch Engines   Allows you to search several search engines simultaneously Examples are Clusty, Dogpile, Mamma, MetaCrawler, and Webcrawler etc  Specialized Search Engine   Help locate specialized subject matter, such as material about movies, health, and jobs Examples are imdb, expedia, rozee, career etc
  25. 25. Emails and More Modes of Communication  Simple Mail Transfer Protocol  Post Office Protocol Version 3  Internet Message Access Protocol