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Internet
Inside the Internet
and the Web
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Topics
The Internet: A Network of Networks
Internet Applications:
Communication and Connection
Inside the World Wide Web
The Evolving Internet
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“It’s a bit like
climbing a
mountain. You
don’t know how
far you’ve
come until you
stop and look
back.”
Vint Cerf
2
The Internet:
A Network of Networks
The Internet is an interconnected network of
thousands of networks linking academic, research,
government, and commercial institutions.
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Internet Services
The Internet provides scientists, engineers,
educators, students, business people, and others with
a variety of services such as:
 Electronic mail (send/receive mail messages)
 Remote login (Telnet - access to other computers)
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Internet Services
 Transferring files (FTP accessing archives of data)
 Newsgroups (Usenet - online public discussions)
 World Wide Web (a
collection of multimedia
documents)
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Counting Connections
Today, the Internet connects computers to about
every country in the world. However, the Internet
is:
 growing too fast to measure its growth
 too decentralized to quantify
 a network with no hard boundaries
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Internet Protocols
The language at the heart of the Internet is
TCP/IP…
 Transmission Control Protocol/Internet Protocol
 Allows cross-network communication
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Internet Protocols
TCP breaks messages into packets
 Each packet has all the information needed to travel
from network to network
 Host systems called Routers determine how to route
transmissions
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Internet Protocols
IP is the address for the packets
 Each Internet host computer has a unique IP Address
 Each address is comprised of four sets of numbers
separated by periods, such as 123.23.168.22
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Internet Access Options
Direct (dedicated) Connection
 Computer has its own IP address and
is attached to a LAN
 No need to dial up
 Files are stored on your computer
 Response time is quick
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Internet Access Options
Dialup Connections
 limited connection using a modem
 Full access dial up uses SLIP or PPP via modem
Broadband Connections
DSL service is newer, faster, and cheaper than ISDN
Can share phone line with voice traffic
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Internet Access Options
Cable Modem Connection
 allow Internet connections using shared TV cables
 can exceed DSL speeds
 Carry increased privacy and security risks
Satellite Connections
 provides connections using DirecTV satellite dishes
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Internet Access Options
Internet Service Providers (ISPs)
 local ISPs provide connections through
local telephone lines
 national ISPs offer connections on a
nationwide scale
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Intranets and Extranets
Intranets - self-contained intra-organizational
networks designed using the same technology as
the Internet
Firewalls - used to prevent unauthorized
communication and secure sensitive internal data
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Intranets and Extranets
A typical Intranets include:





E-mail
Newsgroups
File transfer
Web publishing
Other services
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Intranets and Extranets
Extranets: designed for outside use by customers,
clients, and business partners
Electronic Commerce: business transactions
through electronic networks
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Intranets and Extranets
Electronic data interchange (EDI): a decade-old
set of specifications for ordering, billing, and
paying for parts and services over private
networks.
Virtual private networks: not subject to the
traffic and security problems.
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Internet Applications:
Communication and Connection
The user interface varies depending on which
client/server application is being used.
UNIX - developed by Bell Labs, allows a
timesharing computer to communicate with several
other computers or terminals at once.
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Internet Addresses
E-mail addresses are made up
of two parts separated by an
at(@) sign:
 User name@host name
 Example: [email protected]
The host is named using DNS (domain name system),
which translates IP addresses into a string of names.
“Each person on the “Internet” has a unique e-mail “address” created
by having a squirrel run across a computer keyboard.”
Dave Barry
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Internet Addresses
An Internet address includes:
[email protected]
 username is the person’s “mailbox”
 hostname is the name of the host computer
and is followed by one or more domains
separated by periods:
– host.subdomain.domain
– host.domain
– host.subdomain.subdomain.domain
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Internet Addresses
Top level domains include:
 .edu - educational sites
 .com - commercial sites
 .gov - government sites
 .mil - military sites
 .net - network administration sites
 .org - nonprofit organizations
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Internet Addresses
Examples:
[email protected]
[email protected]
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User President whose mail
is stored on the host
whitehouse in the
government domain
User hazel_filbert at the
server for Lane County,
Oregon, k-12 school
district
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E-mail on the Internet
What appears on the screen
depends on the type of
Internet connection and
mail program you use
Eudora is an easy to use
Email software. Outlook
and Netscape
Communicator are
popular e-mail software
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E-mail on the Internet
Why are free email accounts made available?
 often offered to attract Web site visitors
 available for users of public computers
 sensible for those wanting multiple e-mail addresses
not associated with a workplace
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E-mail on the Internet
EEmail Formats include:
 ASCII text so they can be viewed with any client
program
 MIME that can be used to send and receive text
with enriched text or HTML (displays text
formatting, graphics, and links to Web pages)
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Mailing Lists and
Network News
Mailing lists allow you to participate in email
discussion groups on special-interest topics.
Network News are public discussions that you can
go in and out as you please.
 Messages are posted on virtual bulletin boards (for
everyone to read).
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Real-Time Communication
Internet relay chat (IRC) allows several users to
chat simultaneously
Internet Telephony turns the Internet into a tollfree long-distance telephone service
Video teleconferences allow multi-person
videoconferences via the Web
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Real-Time Communication
See…
Hear…
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Telnet and FTP
Information gathering
Telnet - makes remote login possible
FTP (file transfer protocol) - allows files to be
uploaded and downloaded from remote
computers
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Telnet and FTP
Web browsers locate and
transfer files without
typing commands
When you click a Web link
to download a file, you’re
probably using FTP
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Inside the World Wide Web
WWW is a distributed browsing and searching
system developed at CERN
System was designed to give Internet documents
unique addresses
HTML language was created for encoding and
displaying documents
Browser software was built for viewing documents
from remote locations
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Browsing the Web
Web site Jargon:
Web pages are made up of text and images
A Web site is a collection of web pages
A Home page is the main entry to a Web site
A Web browser like Netscape Communicator or Internet
Explorer allows you to explore the Web by clicking links
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Browsing the Web
Hyperlinks (links) are
words or pictures that
act as buttons, allowing
you to go to another
Web page
Links are typically underlined or
displayed in a different color
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More on Browsing the Web
More Web site Jargon
Links allow you to locate information without
knowing its exact location (it may move from
time to time)
Back and Forward buttons let you retrace your
steps
Bookmarks and Favorites can be set up to mark
your favorite Web locations
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Web Addresses
Pronounced
Earl…like the
name
A typical URL looks like this:
http://www.prenhall.com.beekman
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Web Addresses
Dissecting Web Page address:
Path to the host
http://
www.vote-smart.org/
Protocol for Web pages
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help/database.html
Resource Page
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Searching the Web
Search engines
 produce a list of pages that match a keyword
 they are built around a database that catalogs
Web locations based on content
Directory or Subject Tree
 A hierarchical catalog of Web sites
Natural Language Search Engines
 Allows users to ask for what they want
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“The ability to
ask the right
question is more
than half the
battle of finding
the answer.”
Thomas J.
Watson
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Search Engines
Search engines help find information when you
type a query using keywords.
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Search Engines
Directory/subject tree
engines offer a menu of
subject choices
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Search Engines
Ask questions in a Natural Language Search Engine
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Portals
Portals offer quick and easy access to a variety
of services such as e-mail, chat,maps, news,
shopping, etc.
Examples of consumer portals include
 Yahoo!, Excite, Lycos, Alta Vista, Netscape
Netcenter, Snap
 Specialized portals target specific industries and
economic sectors
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From Hypertext to Multimedia
Typical Web pages can contain:
Tables
Frames
Forms
Downloadable
audio and video
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Streaming audio and video
Real-time live
audio or video
3-D environments
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From Hypertext to Multimedia
Plug-Ins are software extensions that add new
features. Examples include…
QuickTime
Shockwave/Flash
RealPlayer
Acrobat
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Webcasting: Push Technology
Client computers pull information
 Browsers initiate a request for information
Push technology delivers information
automatically to the client computer
 Up to the minute weather reports
 News headlines
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Publishing on the Web
HTML (Hypertext Markup Language)
An HTML document includes
codes that determines the format,
layout, and structure of a Web
document
HTML is not
WYSIWYG
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Publishing on the Web
This text coded as HTML …
<H1>Welcome to Computer Confluence</H1>
<b>Publishing on the Web</b>
Appears like this on
the screen …
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Publishing on the Web
Alternatives to HTML…
Programs that convert document format
features into HTML codes
 Microsoft Word, FileMaker
Web authoring programs
 HomePage, GoLive, FrontPage
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Beyond HTML
Dynamic HTML:
adds more programming power to HTML by
allowing code to automatically modify itself under
certain circumstances
JavaScript:
a simple language for enhancing HTML Web pages
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Beyond HTML
WML
 Wireless Markup Language helps create Web documents
containing stock quotes, phone numbers, and other small
nuggets of information
XML
 Will replace HTML plus provide additional features and
extensions
VRML
 Virtual Reality Modeling Language creates 3-D virtual worlds
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Beyond HTML
Java
 A full-featured, cross platform, object-oriented programming
language
Java applets
 Small Java programs that can be automatically downloaded
onto your client computer and can run on any platform
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The Evolving Internet
Internet2 and the Next Generation Internet
provides faster network communications for
universities and research institutions
virtual laboratories, digital libraries, and distance
learning applications are being built on Internet 2
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Internet Issues
Ethical and Political Dilemmas
Filtering software can prevent unwanted and
inappropriate content
Encryption prevents credit card and e-mail
forgery
Digital cash makes on-line transactions safer
Universal access is a problem
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Internet Everywhere:
The Invisible Information
What Next? Electronic Frontier
A blurring of Web and interpersonal
communication applications
Internet appliances connected to the Web
Continued computer crime and security issues
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