Transcript The World Wide Web

THE INTERNET &
THE WORLD WIDE WEB
Exploring Cyberspace
Shanti Kusumawardhani, MBus.Sys.
[email protected]
History of Internet
Before World Wide Web
 Began in 1969 as ARPANET  linked 4
computers
 In 1974 expanded to 62 computers
 1983  500 computers
 1987  28,000 computers
 Still remain the domain of researchers
and academics
 Information is still all in text
History of Internet
After World Wide Web
 WWW arrived in early 90s
 Multimedia information was made
available
 Introduction of browser
 The web was opened for commercial
uses
 Internet users increased rapidly 
expected to reach 1.8 billions
worldwide this year
Connecting to the internet
You will need 3 things:
 An access device
 A mean of connection
 An internet access provider
The Jargon

Bandwidth - an expression
of how much data can be
sent through a
communications channel in
a given amount of time

Kbps – Stands for Kilobits
per second. For example,
modems transmit at 56
Kbps or 28.8 Kbps.

Broadband – Several
signals can be sent at once
The Jargon

Download - to
transmit data from
a remote computer
to a local computer

Upload - to
transmit data from
a local computer to
a remote computer
Dial-up Connection

Uses telephone
modems to connect to
the internet

Transmission rate:
28.8 – 56 Kbps

Advantages:
◦ Inexpensive
◦ Widely available

Disadvantages:
◦ Low Speed
◦ Dedicated telephone line
Wired Broadband Connection

ISDN (Integrated Services Digital Network
◦ Consists of hardware and software that allow
information to communicated over traditional
copper-wire telephone lines
◦ Transmission rate: 64 to 128 Kbps
◦ A viable solution for single users of small
business networks when other high-speed
options are not available
Wired Broadband Connection

DSL (Digital Subscriber Line)
◦ Uses regular phone lines, DSL modem, and special
technology to transmit data in Megabits per second
◦ Incoming data rate: 1.5-9 Mbps
◦ Outgoing data rate: 128 Kbps-1.5 Mbps
◦ Advantages:
 Always on
 Consistent transmission rate
 Undedicated lines
◦ Disadvantages:
 Access speed and reliability degrade with distance
 Have to choose ISPs that are under contract to your
phone company
Wired Broadband Connection

T1 Line
◦ A trunk line that carries 24 normal telephone
circuits
◦ Transmission rate: 1.5 Mbps
◦ Advantages:
 Multiple users
 Undedicated lines
◦ Disadvantages: very expensive
Wired Broadband Connection

Cable Modem
◦ Connects a PC to a cable-TV like system
that offers an internet connection
◦ Outgoing transmission rate: 1.4 Mbps
◦ Incoming transmission rate: up to 30 Mbps
◦ Advantages:
 Always on
 Speed and reliability do not degrade with distance
◦ Disadvantages:
 Sharing system, connection may be slowed down
during peak-load times
Wireless Broadband Connection

Communications Satellite
◦ A space station that transmits radio waves
called microwaves from earth-based stations
◦ Outgoing transmission rate: 56-500 Kbps
◦ Incoming transmission rate: 1.5 Mbps
◦ Advantages: always on
◦ Disadvantages: rarely available
Wireless Broadband Connection

WIFI (Wireless Fidelity)

3G
◦ Has a transmission rate of 1-11 Mbps up to
300 feet from an access point (hotspot)
◦ The hotspot gets internet access from any
method (DSL, cable modem, T1, etc) then
broadcast it wirelessly
◦ High-speed wireless technology that does
not need access points because it uses the
existing phone system
◦ Transmission rate: up to 300 Kbps
Choosing Your Internet Service
Provider
ISP - a company
that connects you
through your
communications
line to its servers,
or central (host)
computer, which
connect you to the
internet via
another company’s
network access
points
How Does the Internet Work?
1. You connect to the ISP’s POP using a
telephone number that your ISP
provides. A point-of-presence (POP) is a
collection of modems and other
equipment in a local area.
2. ISPs connect to a backbone to access
remote web servers. Backbones are
high-speed, high capacity transmission
lines that use newest communications
technology.
Internet Communications
TCP/IP : the protocol that enables all
computers to transmit data
electronically and to use data
transmitted on the internet
 TCP/IP breaks data into packets
 IP is used to send packets across the
internet to their final destination
 TCP is used to reassemble the packets
in the correct order

How Does the Internet Work?

IP Addresses
◦ Every device connected to the internet has an
address
◦ Each IP address uniquely identifies that device
◦ The address is four sets of 3-digit numbers
separated by periods
 Example: 95.160.10.240
 Each number is between 0 and 255
 Static IP addresses don’t change
 Dynamic IP addresses don’t change
 Since addresses are limited, and most PCs are not
connected a lot of the time, dynamic addresses
are common
Video: Warriors of The Net
What processes happen
when you click a link on The Internet?
The World Wide Web

HTTP
◦ The internet protocol used to access the World Wide Web

HTTPS
◦ The secure version of HTTP

Hypertext Markup Language (HTML)
◦ The language used in writing and publishing web pages
◦ The set of tags used to specify document structure,
formatting, and links to other documents on the web

Hypertext links connect one web document to
another
The World Wide Web

Web Browsers
◦ Your tool for
using the
internet
◦ Comes
preinstalled on
most PCs
◦ 5 basic
elements:





Menu bar
Toolbar
URL bar
Workspace
Status bar
How The Browser Finds Things

URLs: Addresses for web pages
File name & extension
Domain Name
http://
www.pmbs.ac.id/
Protocol for Web pages
Shanti/
home.html
Path/Folder
The World Wide Web

Web portals
◦ A gateway website that offers a broad array of
resources and services, online shopping malls,
email support, community forums, stock
quotes, travel info, and links to other
categories.
◦ Examples: Yahoo, AOL, Microsoft Network
(MSN), Lycos, or Google
22
© 2010 The McGraw-Hill
Companies, Inc. All rights reserved.
The World Wide Web

Search Services
◦ Organizations that maintain databases
accessible through websites to help you find
information on the internet
◦ Examples: portals like Yahoo Search and MSN,
and Google, Ask Jeeves, and Gigablast
◦ Databases are compiled using software
programs called spiders
 Spiders crawl through the World Wide Web
 Follow links from one page to another
 Index the words on that site
Web Search Tools

4 web search tools
◦ Keyword Indexes
 Type one or more search keywords, and you see web
pages “hits” that contain those words
 For phrases with two or more words, put phrase in
quotes
 Examples are Google, Gigablast, HotBot, MSN Search,
Teoma
◦ Subject Directories
 Search by selecting lists of categories or topics
 Example sites are Beaucoup, Galaxy, LookSmart, MSN
Directory, Netscape, Open Directory Project, Yahoo
Web Search Tools
◦ Metasearch Engines
 Allows you to search several search engines
simultaneously
 Examples are Dogpile, Ixquick, Mamma,
MetaCrawler, ProFusion, Search, Vivisimo
◦ Specialized Search Engines
 Help locate specialized subject matter, like info on
movies, health, jobs
Web Search Tools

Multimedia Search Tools
 Allow you to search for nontext resources
Search Tool
Site
A9 (Amazon.com)
http://a9.com
Blinkx
www.blinkx.com
Google
www.google.com/video
ShadowTV
www.shadowtv.com
StreamSage
www.streamsage.com
Virage
www.virage.com
Yahoo!
http://video.search.yahoo.com
26
© 2010 The McGraw-Hill Companies, Inc. All rights reserved.
The World Wide Web
Should you trust all information you find
online?
 There is no central authority that verifies
all internet sites
 Guidelines to evaluate Web resources

◦ Does the information appear on a professional
site maintained by a professional organization?
◦ Does the website authority appear to be
legitimate?
◦ Is the website objective, complete, and
current?
Email
Text messages sent through a computer
network to a specified individual or group. Email
messages can also carry attached files
Incoming email is stored on a mailbox on the
server.
Outgoing email is sent to a Simple Mail Transfer
Protocol (SMTP) server.
Email Addresses
[email protected]
User name/ID: shanti
Domain name: pmbs
Top-level domain: .ac
Two-letter country extension: .id
Internet Telephony
◦ Uses the internet to make phone calls
◦ Long-distance calls are either very inexpensive
or free
 With no PC, dial a special phone number to
packetize your call
 With a PC that has a sound card, microphone,
Internet connection, and internet telephone
software such as Netscape Conference or Microsoft
NetMeeting
◦ Currently inferior in quality to normal phone
connections
◦ Also allows videoconferencing
30
Internet Telephony
Multimedia on the Web
◦ Allows you to get images, sound, video, and
animation
◦ May require a plug-in, player, or viewer
 A program that adds a specific feature to a
browser so it can view certain files
 Example: Adobe Acrobat Reader, RealPlayer,
QuickTime
Multimedia on the Web
◦ Animation
 The rapid sequencing of still images to create the
appearance of motion
 Used in video games and web images that seem to
move
◦ Video
 Streaming video is process of transferring data in a
continuous flow so you can begin viewing a file before
it is all completely sent
◦ Audio may be transmitted either:
 Downloaded completely before the file can be played,
or
 Downloaded as streaming audio
33
© 2010 The McGraw-Hill
Companies, Inc. All rights reserved.
The Intrusive Internet





Snooping – other people CAN read your
emails
Spam – electronic junk mail
Spoofing, Phishing, Pharming
Cookies – little text files left on your hard
disk by some websites you visit
Spyware – Adware, Browser & Search
Hijacker, Key Loggers