Transcript The Internet & the World Wide Web

The Internet & the World Wide
Web
Chapter 2
Exploring Cyberspace
Chapter 2: Key Questions
2.1 What are the means of connecting to the Internet, and
how fast are they?
2.2 What are the three types of Internet service provider,
and what kinds of service do they provide?
2.3 What are the components of an e-mail address, and
what are netiquette and spam?
2.4 What are Web sites, Web pages, browsers, URLs,
and search engines?
2.5 What are FTP, Telnet, newsgroups, real-time chat,
and e-commerce?
To Access the Internet, You Need…
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An access device
A physical connection
An Internet Service Provider (ISP)
Can you give examples of each?
Physical Connection
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Telephone (dial-up) modem
Several high-speed phone lines
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ISDN
DSL
T1
Cable modem
Wireless
Data Transmission Speeds
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Upload – data from local computer to remote
Download – data from remote to local
Bandwidth
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Data that is sent through a communications channel in a given
amount of time
Data transmission speeds:
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Bps – bits per second
Kbps – kilobits per second
Mbps – megabits per second
Gbps – gigabits per second
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8 bits = 1 byte = 1 character
Telephone Modem
See
panel 2.3 on page 39
High Speed Phone Lines
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ISDN (Integrated Services Digital Network)
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DSL (digital subscriber line)
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Hardware & software
Uses traditional telephone lines (128 Kbps)
Always on
Transmission rate is consistent (1.5-8.4 Mbps)
Must live within 3.3 miles of a phone company switching office
T1 line (1.5 Mbps)
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Used by corporate, government, and academic sites
Cable Modems
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Connects a PC to a cable-TV system that
offers Internet access
Always on
Competes with DSL
Transmission rate may not be consistent during
peak hours
Speed:10 Mbps
Wireless Systems
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Communications satellite
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Radio waves (microwaves) transmitted from earthbased stations
Receives data at 400 Kbps & sends data at 56 Kbps
(with phone line)
Other wireless connections
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Radio waves for cellular phones
Sends data up to 155 Mbps
Three Types of ISP Services
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Free-service providers
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Basic-service providers
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NetZero, AltaVista, BlueLight.com
Advertisements and personal info
Offer local connection
Full-service providers
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AOL, Earthlink, MSN
More technical support and international access
How to Get E-mail Software?
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Purchase
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Get as a part of other package
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Netscape Communicator
Provided by your ISP
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MS Outlook express, Lotus Notes
AOL
Free Email Services
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Yahoo, Hotmail
E-mail Addresses
User ID
Domain Name
[email protected]
Domain
Top-level domain Country
(location)
(domain type)
E-mail
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Attachments
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Attached to emails
Formatting preserved
Recipient must have software to read them
Instant messaging
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Cross between e-mail and phone
Message pops up instantly on the screen if user is
logged on
Netiquette
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Use FAQs
Avoid flaming
Don’t shout
Avoid sloppiness
Make attachments small
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Quote only relevant
portion when replying
Avoid spams
World Wide Web
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Uses of the WWW
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E-mail
Entertainment
E-commerce
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E-tailing, auction, online finance, on-line job hunting, B2B
Why the WWW is inviting & easy to use
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Multimedia format : graphics, video, audio, text
Use of hypertext
Web Terms
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Web site
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Web pages
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software that enables users to view Web pages URLs
URLs (Universal Resource Locator)
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a document that can include text, pictures, sound, and video
Browsers
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a computer with a domain name is called a site
a string of characters that point to a specific Web page
Web portals
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Web sites that group together popular features
Web Terms
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Multimedia format
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HTML (hypertext markup language)
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graphics, video, audio, text
A language used to specify document structure,
formatting, and links to other documents
HTTP
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hypertext transfer protocol –rules that allow
browsers to connect with Web servers
Search Engine Types
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Human-organized search sites
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Computer-created search sites
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software "spiders" (software) do the indexing
Northern Light, Excite, WebCrawler, FAST Search, Inktomi
Hybrid search sties
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subject experts (humans) do the indexing
Yahoo!. AOL, MSN, Netscape, Lycos
humans supplemented by computer indexes
AskJeeves, Direct Hit, Go, GoTo.com, Google, HotBot, Snap
Metasearch sites
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sends query to other search tools and compile the results
Go2Net/MetaCrawler, SavvySearch, Dogpile, Inference
Multimedia on the Web
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Plug-ins & helper applications
Multimedia development
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Applets, Java, JavaScript, ActiveX
Text and images
Animation
Video
Audio
More Internet Resources
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FTP – File Transfer Protocol
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Telnet
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a program that allows you to connect to remote computers on
the Internet
Newsgroups
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a program that can transfer files to one compute to another
a giant electronic bulletin board on which users conduct written
discussions about a specific subject
Real-time chat
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participants have a typed discussion while online at the same
time