Transcript What is the Internet?

CSIT 58: The Internet
On the Internet you can:
Send and receive email
 Do research
 Play games or gamble
 Get copies of programs and music
 Get breaking news
 Ecommerce: Buy and sell, bank
 Communicate with chat and phone calls
 And much more…
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What is the Internet?
A world-wide computer network made up
of tens of thousands of smaller networks.
It’s the biggest network of all!
Then what is a network?
Computer Networks
A network is a collection of computers and other
devices that communicate to share data, hardware
and software. A server coordinates the sharing.
Network Servers
A server is a computer running special network
operating system software that allows it to
process requests from other computers that it
is connected to.
Physical Connections
Computers communicate with the server through cable,
phone lines, wireless broadcast or satellite. There are
different types of servers on the Internet for:
web pages
e-mail
ftp (file transfer)
media
Routers
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A router controls connection points
between networks.
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It sends data to the proper
destination and provides security
features.
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If you have multiple PCs at home
with a single cable or DSL Internet
connection, the computers can
share the connection with a router.
TCP/IP Networking
A protocol is a set of rules that determine
how communication takes place.
TCP/IP is the communications protocol
used on the Internet to transfer information
from computer to computer.
 It allows many different types of
computers to exchange data in packets
The Internet Backbone
Network service providers (NSPs) maintain a series
of communications links called the Internet
backbone.
The NSPs are major communications companies
like AT&T, Verizon and Sprint.
No one “owns” the Internet. The computers on it are
owned and operated by individuals and
organizations.
The Internet is decentralized – there is no main
computer that all packets must go through.
ISP Internet Service Provider
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Businesses, organizations and home
users contract with an ISP for access to
the Internet.
An ISP maintains communications
equipment to connect to the backbone.
Sign up with an ISP
Your account with a service provider
usually gives you:
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Access to the Internet
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An email address
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Storage for a web page
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Security features
How to Connect to the Internet
Since the Internet is a world-wide network
of smaller networks, your computer must
become part of that network for you to
have access.
There are several different ways…
Be On a LAN Connected to
the Internet
 The LAHC computer labs are connected in a
local area network (LAN) that gives access to
campus servers for printing and programs.
 The LAN is also connected to the Internet
through a router. Your work may be set up
this way also.
 LAHC pays to connect to high-speed Internet
through a special phone line.
Methods for Connecting
You’re not connected to a LAN at home, so
you need to make a physical connection to
the Internet network through:
Phone lines
Cable TV
Wireless
Satellite (used in remote areas, expensive)
The Phone Lines
Phone companies provide
connection options for homes
and businesses. From slowest
and cheapest on up they are:
•Dial-up
•DSL
• Fiber-optic (FIOS by Verizon)
Dial-up Using Standard Phone
Lines
Phone lines are analog (for sound waves). Computers are
digital. A modem must be installed in the PC to convert the
signals back and forth. Most computers come with one.
A cable runs from the back of the computer to the wall
jack. You can’t talk on the phone while connected to the
Internet.
Modem speeds are 56Kbps (thousands of bits per
second)
DSL
DSL is a high speed connection that runs
over existing phone lines.
You must be within 3 miles of a telephone
switch for it to function well. Contact your
local phone company to find out if it works
in your area.
DSL costs more than dial-up, but is much
faster, up to 1.5 Mbps (M=millions).
Cable TV Internet Access
Connect through cable TV system.
 There are 500 households per neighborhood
connection point for Cox. 2 or 3 big downloaders
can slow response time for everyone.
Speed varies. Can be over 1.5Mbps.
Cable TV and DSL
Cable and DSL Internet require a network
board installed in the PC.
A cable runs from this to an external
modem box or router.
Connection is always-on, when your
computer is on you are on the Internet.
Called broadband because of high data
capacity
Wireless (Wi-Fi)
 A WISP maintains a public wireless network.
 A hotspot is a location where a PC equipped with a
wireless card can connect to the network. Advantage is
portability, no cables are needed.
Available in airports, hotels, restaurants, college
campuses, the LAHC cafeteria, Library and Seahawk
Center.
Disadvantages: slow, not secure, susceptible to
interference
What is the Web?
 The World Wide Web is a collection of data that
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can be linked and accessed using HTTP
HTTP (“hypertext transfer protocol”) is the
communication standard of the Web
A Web page is specially coded document that
can contain text, graphics, videos, and sounds
A Web server is computer that runs special
Web server software and can send Web pages
via Internet
A Web site consists of one or more Web pages
located on Web server
Browser Software
Browser software runs on your PC and
requests and displays web pages
Examples are:
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Internet Explorer (IE)
Mozilla Firefox
Netscape Navigator
AOL
URL
A URL is the address of a web page.
You enter a URL in the browser or click a link to a
page and the browser software requests the page
from the web server.
HTML
Web pages are stored in HTML format (.htm
ending). HTML is a set of instructions that the
browser interprets to display the page.
For example, <U>Internet Backbone</U> would
cause the words Internet Backbone to display
underlined as shown.
How do I use a URL to go to a
Web site?
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To enter a URL:
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Be very precise when entering URL
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Click Address box on browser window
Type URL
Press Enter key
Browser formats and displays page on screen
Don’t use any spaces
Exactly duplicate uppercase and lowercase letters
Complete URL usually starts with http://
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Don’t have to type this, browser fills in
How do I use a URL to go to a
Web site? Cont’d.
The part of a URL after the dot indicates top-level
domain of URL
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Most commercial and e-commerce use .com
domain
.biz and .info are new
Educational institutions use .edu
U.S. government agencies use .gov
U.S. military use .mil
International Web sites use .int or country
abbreviations such as .ca for Canada, or .fr for
France
How do I use links on a Web
page?
 A hypertext link (“link”) is a connection between
two Web pages
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Contains URL of Web page, so it can be used to
“jump” from one Web page to another
Links usually displayed on Web page as underlined
text or as graphic
When positioned over a link, arrow-shaped pointer
turns into
When you click link, Web page displayed
The Stop and Home buttons
 If you don’t want to wait for the Web
page to load, click Stop button (a red X)
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Then click different link or enter new URL
 Click the Home button (a house) to
display the home page set in Tools,
Options
The Refresh button
 Refresh button (one or two curved
arrows) reloads current page from the
server
 If page loads slowly, click Stop button
then click link again or click Refresh
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Sometimes page loads faster
If still slow, try different link or different
URL
The Back and Forward buttons
 Back button (backward pointing arrow) displays
last page viewed
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Click several times to view series of pages
 Forward button (forward pointing arrow) does
not take you to new page but counters Back
button
 When browser first started, Back and Forward
buttons disabled or “grayed” out
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Back button enabled when you go to new page
Forward button enabled after Back button used
The History list
 The History list displays titles and/or URLs of
Web pages you visited in past
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To access IE’s History list, click History button on
right side of Address box or the down arrow next to
the Forward button (IE 7).
In Firefox, click the History button in the menu bar.
 The Site list displays URLs of previously visited
Web sites
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To access the site list, click down-arrow button on
right side of Address box
Use Favorites (Bookmarks)
 To save the link to a page you are viewing:
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For IE version 7 click the button with the plus sign
and star. For earlier versions click the Favorites
button and then Add.
For Firefox, click Bookmark this page in the
Bookmarks menu.
 To visit a saved Web site:
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In IE click the Favorites button (the star) to open list
and clicking page you want
In Firefox click Bookmarks in the menu bar.
Use Favorites Cont’d.
 As you add favorites, you can create
folders to group them into.
 To delete a site or folder from list, rightclick site name, then click Delete on
shortcut menu
How do I print a Web page?
 Click Print button in toolbar or select File, Print
from the menu bar
 Some Web pages include a link to a “print
friendly” version of page
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Designed to use color in way that single page won’t
use all your printer ink
Look for “printer friendly” link before you start
printout
 Use File, Print Preview (in IE7 click the arrow
next to the printer and choose Preview) to make
sure you’re not printing a huge number of
pages.
What should I do when I get
an error message?
 If a Web page can’t be loaded, the
browser eventually displays an error
message
 If a URL is not mistyped, the message
probably means the page has moved,
was renamed, or deleted
 Occasionally a message appears if the
site is too busy to respond – try later
Temporary Files
As you use the Internet, information may
be stored on your hard drive in
temporary files. Delete these to free up
space.
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In IE, go to Tools, Internet Options,
Browsing History, Delete. From there you
can remove temporary files, history, saved
passwords and cookies.
Firefox displays a box asking you to delete
temporary files as they are used. For other
data, go to Tools, Clear Private Data
Plug-Ins
 Non-HTML Web elements – video clips,
animation – might require special
viewing software
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Referred to as plug-ins or helper
applications
Typically downloaded from Web
Popular plug-ins include RealMedia Player,
and QuickTime viewer
Articles I post for you to read require
Adobe Acrobat reader for .pdf format
What is a search engine?
 A Search engine is a site that provides
tools to help find information
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Google, Ask, Live Search and Yahoo!
 Provides list of Web pages based on
keywords you enter in a search query.
 Read my notes on searching and then
practice using search engines in the
assignment.
End of Lecture