Transcript What is the Internet?

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!
So, 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
software that allows it to process requests
from other computers that it is connected
to.
Physical Connections
Computers communicate with the server through
cables, phone lines, wireless broadcast or satellite.
A server may store and forward:
web pages
e-mail
files
media
Who runs the Internet?
No one “owns” the Internet. The computers on it are
owned and operated by individuals,
organizations, and major communications
companies like AT&T and Verizon.
The Internet is decentralized – there is no main
computer that all packets must go through.
How do you get access?
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Businesses, organizations and home
users contract with an Internet Service
Provider (ISP).
An ISP maintains communications
equipment to connect you to the
worldwide network.
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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Email addresses
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Storage for a web page
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Security features
Connecting to the Internet
Since the Internet is a world-wide network
of smaller networks, your computer join the
network.
There are several different ways…
Be On a LAN Connected to the
Internet
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The LAHC computer labs are connected in a
local area network (LAN) that gives access.
The LAN is connected to the Internet through
a router.
LAHC pays to connect to high-speed Internet
through a special phone line.
Methods for Connecting
At home you need to make a 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
Phone
lines are analog (for sound waves). Computers are
digital. A modem is used to convert the signals back and
forth.
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
second)
speeds are 56Kbps (thousands of bits per
DSL
Runs
over existing phone lines.
You must be within 3 miles of a telephone
switch for it to work well.
DSL costs more than dial-up, but is much
faster, up to 1.5 Mbps (M=millions).
Cable Internet
 Speed varies.
There
are 500 households per neighborhood
connection point for Cox. 2 or 3 big
downloaders can slow response time for
everyone.
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.
Available in airports, hotels, restaurants, college
campuses, new buildings at LAHC, the cafeteria,
Library and Seahawk Center.
Disadvantages: slow, not secure, susceptible to
interference
What is the Web?
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The World Wide Web is a collection of linked
web pages
A Web page is specially coded document that
can contain text, graphics, videos, and sounds
A Web site consists of one or more Web pages
located on a Web server
Browser Software
Browser
software runs on your PC and
requests and displays web pages
Examples are:
 Internet Explorer (IE)
 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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Click Address box on browser window
Type URL
Press Enter key
Browser formats and displays page on screen
Be very precise when entering URL
 Don’t use any spaces
 Exactly duplicate uppercase and lowercase letters
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Complete URL usually starts with http://
 Don’t have to type this, browser fills in
How do I use links on a Web
page?
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A hypertext link is a connection between two Web
pages
 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
How do I print a Web page?
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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
 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
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Use Print Preview to make sure you’re not printing
a huge number of pages.
What should I do when I get
an error message?
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If a Web page can’t be loaded, the
browser displays an error message
If the URL was correct the page has
moved, was renamed, or deleted
Occasionally a message appears if the
site is too busy to respond – try later
End of Lecture