Introduction to the Internet

What is the Internet The Internet is a worldwide group of connected networks that allows public access to information and services. 400 million users 200 connected countries 100,000 connected networks 12 million host computers / sites

Who owns the Internet? Each of the networks that make up the Internet is owned by a public or private organisation. No single organisation owns or controls the Internet.

History of the Internet Began in 1969 Network of 4 computers –University of California (Los Angeles) –University of California (Santa Barbara) –University of Utah –Stanford Research Institute

History of Internet Funded by US Department of Defence –Advanced Research Projects Agency (ARPA) Goal 1 –Develop the hardware and software needed to create a geographically dispersed network that could function even if part of the network was disabled or destroyed

History of the Internet Goal 2 –Create a way for scientists at different locations to share information and collaborate on military and scientific projects.

How data is sent over the Internet “Request is sent” 1.Individuals connect from “home” dial in to an ISP using a modem over regular telephone lines –Once connected you can send information or requests over the Internet. –You can request a web page by using its Internet Address (URL)

How data is sent over the Internet “Request is sent” 2.Data is sent over the Internet is divided into packets. –Each packet has destination and origin information

How data is sent over the Internet “Request is sent” 3.ISP uses leased lines from local telephone companies to connect to regional host computers, National ISP’s 4.Request is transfered to a server (a computer directly connected to the Internet that stores and serves data. –All information on the Internet originates within servers

How data is sent over the Internet “Data is received” The server retrieves the requested file, divides it into packages and sends it back to the local ISP. The local ISP routes the packets over the Internet back to your computer The requested file displays on your computer screen

How the Internet Works Divides data into separate parts called packets, and sending them along the best route available to a destination computer. – message –file –document –request for a file

How the Internet Works Each packet contains –data –destination –origin –sequence information used to reassemble data at the destination

Packet Switching breaking a message into individual packets sending the packets along the best route available reassembling the data

Communication Protocol Specifies the rules or standards used to tranmsit data

TCP/IP The software used for packet switching on the Internet is a communication protocol named TCP/IP –Transmission Control Protocol/Internet Protocol

Connecting to the Internet Connect through an Internet Service Provider –An organisation that has permanent connection to the Internet –Provides temporary connections to others for a fee –Internet traffic control is provided by routers, located throughout the Internet

Internet Addresses Each location on the Internet has a four part numeric address called an IP (Internet Protocol) address eg –Geographical region (198) –company or organisation(105) –computer group (232) –specific computer (4)

Domain Names Domain names are the text version of the IP address e.g. –Web Server computer (www) –Organisation (microsoft) –Organisation type (com) International Web sites also include the country code e.g. ca - Canada, au - Australia

Domain Names Domain names are registered in the Domain Name System (DNS) and are stored in Internet computers called Domain Name Servers. Domain Name Servers use the Domain Name to look up the IP address

Domain Abbreviations.comBusinesses.eduColleges and Universities.govGovernment.intInternational treaty organisations.milMilitary.netNetwork and Administrative computers.orgMiscellaneous Organisations

The World Wide Web The collection of hyperlinked documents accesible on the Internet is the World Wide Web (WWW, W3 or the Web) Internet locations containing hyperlinked documents are called web sites

Web Pages A web page is a hypetext or hypermedia document residing on an Internet Computer that contains text, graphics, video or sound. A hypertext document contains hyperlinks to other documents A hypermedia document text, graphics, video or sound hyperlinks to other documents

Web Pages Three types of hyperlinks –Target hyperlinks Move from one location in a document to another location in the same document –Relative hyperlinks Move from one document to another document in the same Internet computer –Absolute hyperlinks move to another document on a different computer

Surfing The ability to branch from one related to another in a nonlinear fashion Like using the remote control to jump from one TV channel to another

Web Pages Created using hypertext markup language (HTML) –set of instructions tags markups –specify links to other documents and how the page is displayed

Web Browsers used to interpret the text coded with HTML tags

Web browser software Web Browser Browser First Browsers used text commands and displayed only text documents Mosaic - displayed documents including graphics and used graphical user interface

Web Browser software Netscape Internet Explorer Once the connection to the Internet is established, the browser program is started.

Browser Software Back and Forward Buttons –Display previously viewed pages Stop Button –Interrupts transmission Refresh Button –Reloads current page

Browser Software Home button –Returns to designated Home Page Search Button –displays web search tool Favourites / Bookmarks –stores locations of favourite Web Site pages

Browser Software Print Button –print all or portion of current page Web address (URL) of current page Links –connections to other sites Address text box –entering a URL in address text box retrieves that page

Home Page the page designated to display each time you launch your browser

Uniform Resouce Locator URL Used by the Browser Address that points to a specific resource on the Internet Indicates –an Internet Site –a specific document at the site –a location within a document at a site

URL For WEB pages, all URL’s start with –hypertext transfer protocol the communications standard used to transfer pages on the web –(because web pages use hypertext)

URL –Protocol; used to transfer data –domain name;identifies computer that stores Web pages (often begins with www) /support/techtips –directory path; where Web page is stored

URL VR100.html –document name;name of Web page #install –anchor name;reference to a specific part of a long document; (always preceded with #)

Browsers - Hyperlinks Hyperlinks to other documents –underlined text of a different color or –a graphic Position pointer over a hyperlink, the mouse pointer changes to a small hand with a pointing finger

Bookmarks / Favourites To return to a page in a future session, record location with a bookmark –title of a Web Page –URL

Searching the Web Search Engine –a search tool; software program that finds Web sites Web Pages Internet Files –that matches one or more keywords Search tools do not actually search the entire Internet

Searching the Internet Search Tools search an index of Internet Sites and documents that is constanntly updated by the company that provides the search tool.

Search Engines Yahoo! Infoseekguide-p.infoseek.com Lycoswww.lucos.com AltaVistawww.altavista.digital.com Excitewww.excite.com WebCrawlerwww.webcrawler.com Four11www.Four11.com

Electronic exchange of messages from one person to another Messages created, sent, forwarded, stored, printed, deleted Must have a mailbox: - usually located on the computer that connects you to the Internet (server operated by ISP)

Internet Mailbox Address combination of : –username –domain name identifies the location of the mailbox computer

Username / Userid unique combination of characters that identifies you sometime limited to 8 characters must be different from other usernames on the same mailbox computer

Username e.g of Internet Address username(gpeacock) domain name(msn.com)

Connecting to Internet & WWW Determine how you will obtain access to the Internet Obtain Necessary Equipment Obtain Necessary Software Install the Software Explore the Internet and WWW