# The Internet <!-- .element: class="r-fit-text" --> Week 4 --- ## Computer Networks  <!-- .element: style="height:400px" --> -- ### What is a Computer Network? A collection of computers that talk to each other. <!-- .element: class="fragment" --> -- ### A Network is Not a Single Entity %3Amax_bytes(150000)%3Astrip_icc()%2Fcity-network-859747880-5b1e8f1704d1cf003c165fe0.jpg&f=1&nofb=1&ipt=6055d0c3b515f2ee629b57183727e10ade1afda29c6ac91a569b170e185b9f04&ipo=images) <!-- .element: style="height:400px" --> NOTE: Imagine the difference between a group chat that can be shut off vs. all your friends chats with each other -- ### Networks are Complex - Modems - Routers - Switches - Firewalls -- ### Not Every Network is the Internet - Local Area Network (LAN) - Virtual Private Network (VPN) - Industrial Control Systems (ICS) -- ### Modems vs. Routers |--|--| |Modems|Routers| |Modulates/demodulates|Routes traffic| |Communicates with ISP|Communicates with local devices| | |Adds security (port forwarding, firewall)| -- ### Review - What is a network? - Is a network a single entity? <!-- .element: class="fragment" --> - Do networks only include computers? <!-- .element: class="fragment" --> - Is every network part of the internet? <!-- .element: class="fragment" --> - Is a modem the same as a router? <!-- .element: class="fragment" --> --- ## History of The Internet  <!-- .element: style="height:400px" --> -- ### ARPANET - Advanced Research Projects Agency Network - 1969 - Defense Communcations Agency (DCA) -- ### World Wide Web - Origin of the www subdomain - 1991 - Tim Berners-Lee -- ### Mosaic - 1993 - University of Illinois - Became Netscape -- ### Mosaic  <!-- .element: style="height:400px" --> -- ### The Internet is **NOT**... - WiFi - The Cloud (we'll get to that later) <!-- .element: class="fragment" --> - Google <!-- .element: class="fragment" --> --- ## The Internet  <!-- .element: style="height:400px" --> -- ### IP Address - Internet Protocol - Like a house number <!-- .element: class="fragment" --> - 127.0.0.1 <!-- .element: class="fragment" --> -- ### URLs - Uniform Resource Locator - Human-readable <!-- .element: class="fragment" --> - Different than Uniform Resource Identifier (URI) <!-- .element: class="fragment" --> -- ### URL Anatomy  <!-- .element: style="height:400px" --> -- ### URLs  <!-- .element: style="height:400px" --> -- ### Review - Can an IP address contain letters? - What does URL stand for? <!-- .element: class="fragment" --> NOTE: - Technically yes, but only if it is IPv6 - Uniform Resource Locator --- ## Now For Some Coding... <!-- .element: class="r-fit-text" --> [Python Lists](/2024/fall/computer-science/slides/python-lists)