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
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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.
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e-mail message
file
document
request for a file
How the Internet Works
• Each packet contains
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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 198.105.232.4
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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. www.microsoft.com
– 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
• .com
• .edu
• .gov
• .int
Businesses
Colleges and
Universities
Government
International
treaty
organisations
• .mil
• .net
• .org
Military
Network and
Administrative
computers
Miscellaneous
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
• 1993 - 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 http://
– hypertext transfer protocol
• the communications standard used to transfer pages
on the web
– (because web pages use hypertext)
URL
• http://www.acme.com/support/techtips/VR100.html#install
• http://
– Protocol; used to transfer data
• www.acme.com
– domain name; identifies computer that stores
Web pages (often begins with www)
• /support/techtips
– directory path; where Web page is stored
URL
• http://www.acme.com/support/techtips/VR100.html#install
• 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
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Yahoo!
www.yahoo.com
Infoseek
guide-p.infoseek.com
Lycos
www.lucos.com
AltaVista
www.altavista.digital.com
Excite
www.excite.com
WebCrawler
www.webcrawler.com
Four11
www.Four11.com
Email
• 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 E-mail Address
gpeacock@msn.com
• 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