The Internet

1. The Internet Computer Studies Higher Grade Grades 11 + 12

2. What is the Internet?wake up Neo… • A world-wide network of • Computers and • Computer networks • Connected via telephone lines or other mediums • In order to provide certain services • To those connected to the network http://www.exclaim.it/glossary.php?firstletter=A

3. What do I need to connect to the Internet? • A computer • A modem • An account with an ISP • A phone line A modem converts digital signals from your computer into analogue signals that can be transmitted via phonelines

4. How does the Internet Connection work? • Your computer connects to your ISP using your modem and your phone-line • Once your ISP has verified your user-name, password and account details you are ready to use the Internet • You ask your ISP to get web-pages and e-mails for you and it does the job and sends the data back to your computer • Your ISP accesses information on your behalf

5. How? • Web-pages are stored on web-servers all over the world. • When you want a web-page your ISP knows where to find it and goes and fetches it for you. • Your browser then displays it on your screen. • Your ISP also locates other resources such as other e-mail servers and chat servers.

6. Diagram of the whole thing Your PC Web-Server Another PC YOUR ISP Another ISP Chat Server Web-Server The other ISP is in reality also connected to the other servers

7. Still confused? • Check these sites out: • http://computer.howstuffworks.com/internet-infrastructure.htm • http://www.learnthenet.com/english/animate/connect.html • http://www.mids.org/what.html

8. Two types of connections • It is possible to have a permanent connection (leased line), and this often the situation in large business organizations and universities • Other users use a modem that converts digital signals of a computer to the analogue signals required for normal voice-carrying telephone lines

9. Things to do on the Internet • World Wide Web (WWW) • Electronic Mail (e-mail) • Newsgroups (Mailing Lists) • File Transfer Protocol (FTP) • Telnet • Internet Relay Chat (IRC)

10. World Wide Web • A collection of multimedia documents connected with hyperlinks • Largest growing area of the Internet • Popularity is high due to it’s easy to use interface

11. World Wide Web 2 • Web-sites are made up of inter-related web-pages • These pages are connected using hyper-links • Hyper-links are text or images that you click on to display a related web-page

12. World Wide Web 3 • You need a web-browser to access web-sites on the Internet • A web-browser is a program that displays web-pages and their related links in a window with an easy to use interface • Web-browsers allow you to go back to a previously visited page, print web-pages and keep a list of your favourite and regularly visited web-sites

13. World Wide Web 4 • Each web-site has a unique address sometimes referred to as the URL (Uniform Resource Locator) • Each URL consists of various parts separated by dots (.) or slashes (/) • See example on next slide

14. World Wide Web 5 http://www.cs.uct.ac.za/~dgruijte/index.html • http – Hyper Text Transfer Protocol… this tells the web-browser that you’re accessing a web-site • www – World Wide Web • cs.uct – The domain name… usually linked to the institution involved • ac – Academic institution • za – South African • /~dgruijte/ - Location of web-page on the domain • index.html – web-page to be viewed

15. Some domains • .gov – government sites • .org – organisations • .com – usually big businesses • .net – usually soley internet based organisations or groups • .edu – education (also .ac) • .co.za – South Africa Site • .co.uk – UK Site

16. World Wide Web 6 • There are two ways of getting to a web-site • Typing the address straight into the address-box in your web-browser • Using a search engine

17. World Wide Web 7 • Typing the address into the address box

18. World Wide Web 8 • Search Engines • You type in what you’re looking for and the search engine will search the web for all web-pages related to your search • The search engine then displays the results as hyper-links which you can click on to view the web-sites

19. World Wide Web 9 • Many, but not all search engines allow you to use so-called Boolean operators to refine your search. These are the logical terms AND, OR, NOT, and the so-called proximal locators, NEAR and FOLLOWED BY. • Boolean AND means that all the terms you specify must appear in the documents, i.e., "heart" AND "attack."  You might use this if you wanted to exclude common hits that would be irrelevant to your query.  • Boolean OR means that at least one of the terms you specify must appear in the documents, i.e., bronchitis, acute OR chronic.  You might use this if you didn't want to rule out too much. • Boolean NOT means that at least one of the terms you specify must not appear in the documents. You might use this if you anticipated results that would be totally off-base, i.e., nirvana AND Buddhism, NOT Cobain. • + and - Some search engines use the characters + and - instead of Boolean operators to include and exclude terms.

20. World Wide Web 10 • NEAR means that the terms you enter should be within a certain number of words of each other.  FOLLOWED BY means that one term must directly follow the other. ADJ, for adjacent, serves the same function. A search engine that will allow you to search on phrases uses, essentially, the same method (i.e., determining adjacency of keywords). • Phrases: The ability to query on phrases is very important in a search engine. Those that allow it usually require that you enclose the phrase in quotation marks, i.e., "space the final frontier." • Capitalization:  This is essential for searching on proper names of people, companies or products. Unfortunately, many words in English are used both as proper and common nouns--Bill, bill, Gates, gates, Oracle, oracle, Lotus, lotus, Digital, digital--the list is endless.

21. World Wide Web Services • The following are available on the WWW • Research and Education • News • Shopping • Banking • Games and Hobbies • Advertising • Communications

22. Electronic Mail • Sends messages containing text, pictures and other media • Each e-mail address is unique • An e-mail server (usually your ISP) manages your e-mail address for you • Web-based e-mail servers are also available e.g. hotmail.com, webmail.co.za • When an e-mail is sent to an address the e-mail actually gets sent to the ISP that hosts that e-mail address and not directly to the user

23. Example • Your ISP is MWeb • You send an e-mail to bob@iafrica.com • When you click “send” the e-mail is sent to your ISP’s e-mail server • Your ISP looks at the address and sees that the e-mail must be sent to someone at iafrica.com • The e-mail is then transferred to the destination server • Bob checks his e-mail • When Bob checks his e-mail his e-mail client sends a request to his ISP asking if there is any e-mail for him • Because his e-mail is kept on the iafrica server his ISP knows immediately if there are new messages. • These messages are then sent from iafrica.com to Bob’s pc.

24. Diagram Your PC You send an e-mail from your PC to bob@iafrica.com MWeb Your ISP sends the e-mail to the destination e-mail server Bob checks his e-mail iAfrica Bob’s PC

25. Web-mail • Web-mail works much the same way • The only difference is that the e-mail stays on the destination server • The user has to use a web-browser to read, send and manage those e-mails on the server.

26. Advantages of E-mail • Faster • More reliable • Can send to multiple people at once • Multimedia attachments • Cheaper

27. Disadvantages of E-mail • Viruses! • Impersonal • Not everyone has an e-mail address • Spam • Spam • Spam

28. Newsgroups • Newsgroups are places for people to post messages of a common topic. • Any user can view the news group and read the messages there. • The messages stay permanently on the newsgroup and each user must check the newsgroup for new messages. • Any user can post a message to the news group. • Requires you to have a news-reader installed.

29. Mailing Lists • A list of e-mail addresses identified by a single name, such as students@uct.ac.za • When an e-mail message is sent to the mailing list name, it is automatically forwarded to all the addresses in the list. • When you subscribe to a mailing list then your e-mail address is added. • When someone sends a mail to the mailing list then all members of the list receive it. • You can send to the mailing list simply by sending your e-mail to the list address. • This requires only an e-mail client and no special software.

30. Internet Relay Chat • These are more commonly known as chat servers. • The user uses a chat client to connect to a chat server. • Once connected to that chat server the user can join a number of chat-rooms or channels of interest. • When a user types a message it is broadcast to all users currently in that room/channel. • Private chats are also possible. • http://www.mirc.co.za – Give it a try!

31. Telnet • A way of remotely using another computer! • A telnet client is used to connect to another machine on the internet. • You can then use that machine exactly like you would if you were sitting right at the machine.

32. Software on the Internet • Freeware • This is totally free software that you never have to pay for :) • Source-code is often included • Shareware • Programs with limited functionality or limited time period which you may use • Allows you to try a program out before you buy it • Upgrades • Download upgrades for existing software • Microsoft Updates (waste of time and bandwidth)

33. Creating your own web-site • You need • Web Authoring software • Dreamweaver, Frontpage, notepad • A domain name • www.mykewlpage.co.za • A web-server to host your web-site on Your ISP usually will provide the last two items.

34. End If you want more info take a look at: http://computer.howstuffworks.com/channel.htm?ch=computer&sub=sub-internet