Chapter 8 The Internet: A Resource for All of Us

The Internet n “network of networks” -- technology for linking computers into a world-wide network n every connected computer can directly exchange data with any other computer on the network –uses packet switching principles –each machine has its own unique IP address –type of computer does not matter

Internet History n ARPANET established connections between 4 computers (UCLA, UCSB, Standford, Univ of Utah) n invented by Ray Tomlinson n term Internet used to describe a connected set of networks n development of the World Wide Web –Tim Berners-Lee creates a system to distribute research results over the Internet

Internet organization and administration n no controlling authority for the Internet n management of the Internet is distributed throughout the network n participating computers and networks agree to implement the Internet protocols for sharing resources

Why has the Internet become so popular? n universal TCP/IP standard n ability to link sites (Web) n easy access to resources via graphical browsers n increased use of PC’s and networks at work and home

Accessing the Internet - Client/Server n server - software and/or hardware installed on the computer where the information being accessed is stored –allows the user to get the information –the computer system being accessed may be anywhere in the world n client (browser) - the piece of software that requests information from the server –runs on user’s computer –Mosaic - first graphical browser - Marc Andreessen –Netscape, Internet Explorer

Web Terms n Web server - software that responds to client (browser) requests n Web site - collection of related Web documents n home page - document first encountered at a particular Web site (usually an index or table of contents)

Browser Terms n default start page - located at the browser vendor’s home server –can be changed n history list - list of previously viewed sites –quick way to go back to a particular site n favorites/bookmarks - allows user to save addresses of frequently visited sites n plug-ins - software that enhances the capability of a browser to access Web resources

Web addresses n URL (Uniform Resource Locator) - an address that uniquely identifies the location of a Web document n URLs have 4 parts: (not all parts are required) –protocol - Internet standard used to access document (http, ftp, gopher, etc.) –server - Internet domain name of the server on which the document is located –path - specific directions for finding the document on the computer (folders and subfolders) –resource name - actual filename of the document n

Finding Information on the Web n subject guides (directories) - lists of sites organized by content and selected by human researchers –examples: n search engines -software that allows users to search databases that index large portions of the Web –searches often hampered by ambiguity of English language –search operators and words not fully standardized –examples:AltaVista, Google, Infoseek, Lycos

Reliability of information on the Web n Just because something is on the Web does not make it true. Ask yourself some of these questions. –Who wrote the page? –Who sponsored it? –What is the purpose? –Is it objective? –Are the sources reliable? –Is the data accurate? –Is the data up-to-date?

Other parts of the Internet n Usenet - informal network that allows the posting and reading of messages in newsgroups that focus on specific topics n FTP (file transfer protocol) - a standardized method for transferring files –downloading - transferring a file from the remote (server) system to your local machine can result in a virus infecting your computer –uploading - transferring a file from your local machine to the remote (server) system n telnet - software that allows a PC to connect to a host computer on the Internet and emulate a local terminal

Electronic mail n created by Ray Tomlinson in 1972 n mail server - receives and stores incoming mail n client - software running on your computer; allows user to read, compose, send, save, delete and print messages n address -

Addresses n addresses have 2 parts connected by symbol l user name (mailbox name) l identifies owner of account l domain name (server address) l identification of the computer system on which your account resides n examples:

Netiquette n Netiquette - term coined to describe appropriate behavior when using the Internet – examples include a brief, meaningful subject line don’t write in anger (flame) be aware that attachments can be used to transmit viruses never respond to junk (spam) use emoticons (smileys) to help communicate meaning ex: ;-) :-( :-o –other examples observe copyright restrictions observe privacy and system use rules

What you should know n you may not have a right of privacy at work or at school n backup copies of are sometimes kept for several years n written communication is NOT the same as oral communication –emoticons can help clarify meaning

accounts at UNLV n Computer accounts can be generated on Pioneer –mainframe that runs Unix OS –assigned a login and password login becomes the user name portion of your address address is password can be changed on Web n Once an account is set up you will have access to on the Web –