1. Computer Network ( 電腦網絡 ) n A computer network is set of two or more computers connected together. n Advantages: –communicating with other users –sharing resources (e.g., files, printer)

2. Local Area Networks (LAN)

3. Wide Area Network (WAN) High Speed Link as a Backbone LAN

4. Internet ( 國際互聯網 ) n A global interconnection of networks n connection via: –telephone lines –optical fibers –radio links

5. Internet Terms n Modem (Modulator/demodulator) –an electronic device for converting between serial data from a computer and audio signal suitable for transmission over telephone lines

6. Internet Terms n Modem (Modulator/demodulator) Types: –external modem –internal modem –wireless modem

7. Internet Terms n TCP/IP TCP/IP –data are broken down into packets and sent across the Internet, it is then recombined and checked the correctness of data. n UNIX –a multi-user, multitasking operating system developed in AT&T Bell Lab. –a system software used by most server.

8. Internet Terms n ISP ( 網絡供應商 ) –a business that supplies Internet connectivity services to individuals and other organisations Example –IMS –CTI –iCable

9. Internet Terms n DNS ( 網域名稱系統 ) Domain name address –used by human users –e.g., “www.hknet.com” IP address –used by packet routing software –e.g., “202.67.240.222”

10. Internet Terms n URL ( 劃一資源定位器 ) –address for a document or site on the Internet e.g., http://www.hssc.edu.hk/~f98123/ n HTTP ( 超文本傳送協定 ) HTTP –the client/server protocol used to access information on the WWW.

11. Internet Terms n POP ( 郵局規約 ) –Post Office Protocol –a standard used in receiving email n SMTP ( 簡單郵遞傳送規約 ) –Simple Mail Transfer Protocol –a standard used in sending email

12. Internet Terms n HTML ( 超文本標記語言 ) –a language used for documents on the WWW. Example …

13. Internet Resources n Email ( 電子郵遞 ) –message sent and received electronically via telecommunication links between computers. n World Wide Web ( 全球資訊網 ) –uses a multimedia interface to link to resources located worldwide

14. Internet Resources n Newsgroup ( 新聞組 ) –a topic-specific forum where people can post questions, news, and comments, or read and respond to such postings n IRC ( 互聯網傳達對話 ) –a service that enables an Internet user to participate in a conversation online with other users.

15. Internet Resources n BBS ( 電子公告欄 ) –a system equipped with one or more modems or other means of network access that serves as an information and message-passing centre for remote users.

16. Internet Services n Telnet –runs programs on remote computers n FTP (File Transfer Protocol) –transfers files between local and remote computers

17. file TCP/IP ClientServer

18. HTTP Server Client WWW modem broadband adaptor

19. Free n Web Space –http://xoom.com/webspace/ n Web Counter –http://fastcounter.linkexchange.com/ n Guest Book –http://www.guestbook.de n Graphic Files (gif, applet, …) –http://www.rogergifs.com/graphics.html