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What is the purpose of the internet?
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Examples
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Communications - email, messengers, FaceBook, News, Skype, etc.
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Multimedia - videos, graphics, and sound
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Information - pictures, libraries, e-books, webpages, etc.
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Entertainment - games
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E-commerce - shopping, insurance, banking, etc.
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The U.S. military invented the internet
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Arpanet - to allow scientists at difference locations to share information through a computer network
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Funded by the Pentagon's Advanced Research Projects
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Started functioning in September 1969
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Goal - network still functions if part of network is destroyed. Why?
If a war destroyed a city (or hub point) of the network.
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node - a connection point
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1969 - four host node points
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1984 - more than a 1,000 host node points
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Today - more than 200 million
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Can this growth continue?
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No, there is an upper limit. Similar to telephones. If limit on telephones are reached, then add more digits.
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No government controls the internet. It is world wide
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Several organizations
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World Wide Web Consortium (W3C) - sets standards on the internet
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www.w3.org/
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Internet2 - tests advance, new technologies
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Internet Connections
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Dial up access - use telephone line for internet access
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Very slow
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High speed connections
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Digital cable (DSL, ADSL, or modem), wireless (or wi-fi), or satellite modems
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Internet Protocol (IP) - a unique number that identifies a computer on the internet
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Number is an address
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Two different websites cannot have the same number
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IP is 98.136.92.79 for my website
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An IP is 32 digits
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Four numbers that range from 0 to 256
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Computers are either on or off (two states)
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Possible websites = 2 32 = 4,294,967,296
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Domain - name for website
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Domain names also have to be unique
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My website: www.ken-szulczyk.com
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Go to who.is website to find ownership of domain names
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Why do people use domain names instead of IP?
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Easier to remember
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Packets - information is passed in small files, 1,000 or 1,500 bytes
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Routers - receives a packet and re-transmits
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Has sender's and recipient's IP address
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Routers have tables to determine where to send
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Routers handle up to 60 million packets per second
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Similar to a torrent
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Web browsers
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Uniform Resource Locator (URL) - the web address displayed in the browser
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As of August 2010
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Firefox Mozilla 45.8%
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Internet Explorer Microsoft 30.7%
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Chrome Google 17.0%
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Safari Apple 3.5%
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Opera 2.3%
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Handheld devices can display webpages
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Ipads,Epads, and cellular phones
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Iphone and Google's Android
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Called Microbrowsers
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Can use slim down versions of browsers above
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Websites and homepages
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A website has a homepage
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Called index.php or index.htm
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You never enter this. When you go to a website, this is the fist page that is loaded
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Website may have links that branch from the main page
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Link - connection to any webpage
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More will be said at the end of the course
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Websites vary in design
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Ranges from simple designs and content to very complex
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Types of Websites
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Portal - offers services like free email, weather, etc.
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News - website geared for news
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Informational website - information from government or organizations
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Business/Marketing site - sells products and services
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Educational - teach and train; universities, colleges, and employer training
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Entertainment - games, videos, music, etc.
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Advocacy - websites geared for a cause
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Blog - opinions of website's author
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Personal website - people show the world their interest
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Search Engines - a website that allows people to find specific web content on the internet
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Keywords - are the search criteria
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Every website differs in how websites are referenced and indexed
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Businesses pay money to search engines to display their website at the top of the list
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Most popular search engines
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Google 85.4%
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Yahoo 6.3%
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Bing (Microsoft - replaced MSN) 3.3%
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