1.  Internet: a network of network  The internet consists of thousands of smaller networks  They may be educational, commercial, nonprofit, military organizations, etc. 2-1

2.  Internet History  Began with 1969’s ARPANET for US Dept. of Defense  62 computers in 1974  500 computers in 1983  28,000 computers in 1987  Early 1990s, multimedia (www) became available on internet 2-2

3. NAP-A IP: A.0.0 2-3 NAP-B IP: B.0.0 NAP-C IP:C.0.0 NAP-E IP:E.0.0 Amazon.com Server IP: A.AS.0 NAP-D IP:D.0.0 ISP2/POP-1 IP:B.1.0 ISP2/POP-6 IP:B.6.0 Udel-4 IP:C.4.0 Comcast/POP-3 IP:D.3.0 Comcast/POP-5 IP:D.5.0 ISP1/POP-2 IP:E.2.0 PC-a IP:B.1.a MAC-a IP:B.6.a MAC-a IP:C.4.a PC-b IP:C.4.b PC-b IP:D.5.b PC-a IP:D.5.a MAC-a IP:D.3.a PC-b IP:D.3.b PC-a IP:E.2.a MAC-d IP:B.6.d MAC-b IP:B.6.b MAC-c IP:B.6.c PC-d IP:E.2.d PC-b IP:E.2.b PC-c IP:E.2.c

4.  NAP (Network Access Point): A routing computer at a point on the internet where several connections come together  Connects to the Internet Backbone (fast, expensive connection)  Router: A device that forwards data from one network to another based on internal routing tables  Routers read each packet’s destination IP address and decide how to forward it.  IP Address: Internet Protocol Address – a unique address that identifies every computer and device connected to the internet  POP – Point of Presence – A local access point to the internet  ISP: Internet Service Provider – A local, regional, or national organization/company that provides access to the internet  LAN – Local Area Network – a computer network that spans a relatively small area 2-4

5.  Protocols  set of rules and encoding specifications for sending data  Internet uses TCP/IP (Transfer Control Protocol/Internet Protocol ▪ Used for all internet transactions  TCP – Deals with Transfer of Data – how it is broken up and reassembled to be sent across the internet  Packets ▪ Fixed-length blocks of data for transmission ▪ Data transmissions (files) are broken up into packets ▪ Not all packets from the same file will follow the same pathway ▪ Data must be reassembled at the other end 2-5

6.  IP – Deals with the addressing and pathways the data travels over the internet  IP Addresses  Every device connected to the internet has an address  Each IP address uniquely identifies that device  The address is four sets of 3-digit numbers separated by periods ▪ Example: 95.160.10.240 2-6

7.  The Internet is Distributed  No centralized control of the internet ▪ If any one computer goes down, the internet can continue to function  Allows for expansion of the internet as well  Can easily add new computers and networks to the internet. ▪ Must assign unique IP addresses to computers connecting to the internet and ▪ Must update Router Tables 2-7

8.  Client/Server Model  Client: a computer requesting data or services  Server: a host computer, a central computer supplying data or services requested of it ▪ Services can be requested over the internet ▪ E.g., Check your bank account  A client program on your computer forwards your request to a server program at your bank. The bank server sends the info back to your client program  Often multiple clients share the services of one server ▪ Or Services can be local requests ▪ Maybe one computer on a local network has extra disk space and can hold a large database ▪ Clients on the network make requests from the local server and the server sends only the data the client requests  Peer to Peer (P2P) Model  Computers that both provide services to and receive services from each other ▪ Services execute on a temporary basis ▪ E.g., Instant Messaging, 2-8

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10.  The World Wide Web:  Browsers ▪ Software for web-surfing ▪ Examples: Internet Explorer, Netscape Navigator, Mozilla FireFox, Opera, Apple Macintosh browser, Safari ▪ Browsers do 2 key things: ▪ Locate web sites via unique addresses ▪ Read web pages and display them 2-10

11.  Website ▪ A location on the web that has a unique address and a set of interconnected web pages, usually on the same server ▪ Example: www.barnesandnoble.com, www.eecis.udel.eduwww.barnesandnoble.com www.eecis.udel.edu ▪ The website could be anywhere ▪ not necessarily at company headquarters 2-11

12.  Web Pages  The documents and files on a website  Can include text, pictures, sound, and video  Home page  The main entry point for the website  Contains links to other pages on the website 2-12

13.  (URL)  A string of that points to a specific (unique) on the web  URL =  It consists of ▪ The web protocol - ▪ The of the web server ▪ The directory or on that server ▪ The file within the directory, including optional extension ▪ http://www.imageek.com/girlgeek/java.htm 2-13 protocol domain name file name. extension directory

14.   Must be unique  Identify the, and the type of it is ▪ www.whitehouse. is NOT the same as www.whitehouse. www.whitehouse. ▪.gov,.org,.edu, etc. 2-14

15.   The used to access the World Wide Web  Stands for   The version of   The language used in writing and publishing  The set of tags used to specify document structure, formatting, and links to other documents on the web  NOT a programming language (but it can contain programming code)  connect one web document to another 2-15

16.   Organizations that maintain accessible through websites to help you find on the internet  Users can ask questions or use to locate information  Examples: Google, Ask Jeeves, and Gigablast  are compiled using software programs called ▪ crawl through the World Wide Web ▪ Follow links from one page to another ▪ the words on that site 2-16

17.  There is no that verifies all internet sites  Should you information you find online?  Guidelines to evaluate Web Resources  Does the information appear on a maintained by a ?  Does the website appear to be legitimate?  Is the website,, and ? 2-17

18.  Email Program  Examples: Microsoft’s Outlook Express, Mozilla’s Thunderbird, Apple’s Apple Mail  Enables you to send email by running email software on your computer that interacts with an email (usually at your )  mail is stored on the in an electronic mailbox  Upon, mail is sent to your 2-18

19.  Using email 1. Get an, following the format Joe_Black@earthlink.net.us Joe_Black@earthlink.net.us 2. Type addresses carefully, including capitalization, underscores, and periods 3. Use the to avoid addressing mistakes 4. Use the to store email addresses 5. Sort your email into or use 2-19 User Name Domain name

20.  2 for transferring mail from the to the :   I  1 for transferring mail from  2-20

21.  – (NOT to be confused with Point of Presence!)  How this works: 1. – holds your mail 2. – logs on and requests mail 3. – downloads all mail to the client (your computer) 4. – removes your mail 5. can disconnect – you’ve got all your mail now!  Advantages: ▪ Don’t need to stay to the for long ▪ are used minimally ▪ More software is currently available for 2-21

22.   How this works: 1. – holds your mail 2. – logs on 3. – downloads email headings (subject) only ▪ reads mail on the ▪ chooses which mail to and ▪ Mail remains on 2-22

23.  Advantages: ▪ You can your anywhere, from any computer ▪ Faster time (not all your email files) ▪ Good for ▪ Ability to handle (e.g., MIME messages) ▪ can act like – functionally is a superset of 2-23

24.  :  Your limits your  You use and only to read your email  You can only stay to the for a limited amount of time  Your server has  :  You travel or check your from more than one  You get a lot of and don’t want to it all to your computer  You want to your messages  You can maintain a to your  You have a lot of on your 2-24

25.   used to transfer data from one to another  Uses  Think of it this way: When you send an email message out, it uses to travel to. When you want to read an email, you use or to get the email message from the. 2-25

26.   Any user on a given email system can send a message and have it pop up instantly on the screen of anyone logged into that system   Participants have a typed discussion while online at the same time  is one-on-one, but has a list of participants 2-26

27.   A software standard for transferring between computers with different Operating Systems   A giant electronic discussion board  Usenet is the of servers on the internet www.usenet.comwww.usenet.com  To participate you need a   An email-based  Uses an automatic that sends to subscribers on selected topics 2-27

28.  Internet Telephony  Uses the internet to make  Long-distance calls are either very inexpensive or free  Currently to normal phone connections   Programs that scour the web and pull together from several to one place   Short for, a diary-style web page  Have become popular, both privately and in politics   Recording internet radio or similar internet audio programs  Some radio stations their audio programs over the internet 2-28

29.   Conducting business activities online  is business-to-business e- commerce  now involves online banking, stock trading online, and e-money such as PayPal  Online link buyers with sellers ▪ is the most well-known example of person- to-person 2-29