The Internet
What is the Internet? The Internet involves millions of computers, connected in complex ways to a maze of local and regional networks
Origins of the Internet 1969 Department of Defense established experimental network connecting 4 research computers (UCLA, Stanford Research Institute (SRI) , UC@Santa Barbara and U. of Utah. Called ARPANET 1980s National Science Foundation involved Only scientific, research and academic institutions (no commercial traffic)
Other Developments… 1989 - E-mail connectivity thru CompuServe and MCI Mail 1991 – move towards private sector National Access Points (NAPs) Internet Service Providers (ISPs) Communication coordinated through national and international organizations (standards)
Who Owns the Internet? No one company or country can be considered as owner of Internet Ownership shared among various entities Coordination: Internet Society (ISOC) Internet Engineering Task Force (IETF) Internet Architecture Board (IAB) In the US – ICANN – Internet names and port numbers (Internet Corporation for Assigned Names and Numbers)
Cost ($$$$)… Revenue is required to offset expenses Servers, routers, communication lines, etc. Costs must be covered by users Companies, organizations and individuals AOL – subscribers charges monthly fee
Difference Between Internet and Web? World Wide Web is the Multimedia portion of the Internet Images, video, sound, animation, etc. Early 1990s
Internet Address Logical name for computing system www.scranton.edu Domain Name Logical name for computing system www.scranton.edu Top-Level Domain (suffix) ICANN IP Number 32-bit address (4 part decimal #) ARIN (American Registry for Internet Numbers)/ RIPE / APNIC 132.161.33.60
Internet Address… Ethernet Address 48-bit address built into machine or Ethernet board Refers to specific board in a local computer
Ethernet Address (physical) Addressing Domain Name Server (local) Network Information Server (wider area) Maintain databases with domain names and IP numbers in binary format Domain Name IP Number (logical) Ethernet Address (physical)
Laptops Static IP address Dynamic IP address Specified manually and entered into network tables Dynamic IP address Dynamic Host Configuration Protocol (DHCP) Ask network for an IP address when you turn it on (from a pool of available addresses) IP address changes each time computer is used
Web Browsers Internet Explorer, Mozilla, Netscape Navigator, Firefox System of communicating Web documents Hypertext Transfer Protocol (HTTP) Formatting instructions called: HTML (Hypertext Markup Language)
HTML Tags <html> </html> Begin/End of document <b> </b> Bold <p> </p> Paragraph <title> </title> Title – top of window <table> </table> Use in tabular form <ol> </ol> Ordered List <br> Break (new line) <img src=“mypicture.gif”> Image
JavaScript – for Interactivity Allows for local processing (on your machine) instead of on server (server-side processing) Browser handles some processing chores Client-Side Processing Buttons, Check boxes, drop-down lists Advantage Faster response to user interaction Disadvantage Opens user to possible risks