csce 101 introduction to computer concepts the internet & the world wide web chapter2

CSCE 101 Introduction to Computer Concepts

The Internet & the World Wide Web

Chapte

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The Internet & the World Wide Web

Exploring Cyberspace Connecting to the Internet How Does the Internet work? The World Wide Web Email & Other Ways of Communicating over

the Net Telephony, Multimedia, Webcasting, Blogs,

E-Commerce Snooping, Spoofing, Phishing, Pharming,

Cookies, & Spyware

Chapte

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The Internet

Internet History Began with 1969’s ARPANET for US Dept. of Defense 62 computers in 1974 500 computers in 1983 28,000 computers in 1987 Early 1990s, multimedia became available on internet

To connect you need An access device (computer) A means of connection (phone line, cable hookup, or

wireless) An Internet Service Provider (ISP)

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Connecting to the Internet

Bandwidth Is an expression of how much data – text, voice,

video and so on – can be sent through a communications channel in a given amount of time

Baseband Is a slow type of connection that allows only one

signal to be transmitted at a time. Broadband

Is a high speed connection that allows several signals to be transmitted at once.

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Connecting to the InternetDigital Data Units

bit (b) Smallest unit of information used by computers, can be 0 or 1

Byte (B) A group of 8 bits, which represents one character, digit, or other value

Kilo (K) About 1,000 (210 = 1,024 exactly)

Mega (M) About 1,000,000 (220 = 1,048,576 exactly)

Giga (G) About 1,000,000,000 (230 = 1,073,741,824 exactly)

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Connecting to the InternetData Transmission Speeds

Originally measured in bits per second (bps) 8 bits are needed to send one character, such as

A or a Currently measured in kilobits per second (Kbps) Kilo- stands for a … A 28.8 Kbps modem sends 28,800 bits per second How many characters per second would that be?

Mbps connections send 1 million bits per second Gbps connections send 1 billion bits per second

28,800 / 8 = 3600 characters per second

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Connecting to the InternetModems

Modem (from modulate and demodulate) is a device that modulates and demodulates an analog carrier signal to encode/decode digital information.

Dialup Modems (28.8 Kbps - 56Kbps) Can be either internal or external to your PC Most ISPs offer local access numbers Need call waiting turned off; either manually or in

Windows

Audio coupledInternal modem

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Connecting to the InternetModems Modems (Dialup) High-speed phone lines

ISDN line Integrated Services Digital Network Allows voice, video, & data transmission over

copper phone lines Can transmit 64 to 128 Kbps

DSL (Digital Subscriber Line) Uses regular phone lines, DSL modem Receives data at 1.5-9 Mbps; sends at 128Kbps –

1.5 Mbps Is always on

DSL modem

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Modems (Dialup) High-speed phone lines (ISDN line, DSL line) Cable Modems

Cable Internet access, along with DSL technology, are the two primary types of broadband Internet access.

Bit rate of business: 2 Mbps to 50 Mbps or more. Bit rate of residential: 384 Kbps to 20 Mbps or

more. Few attempts to offer different service tiers

beyond the traditional 'home' and 'business' designations.

Cable modem

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Modems (Dialup) High-speed phone lines (ISDN line, DSL line) Cable Modems Satellite

Always-on connection using satellite dish to satellite orbiting earth

Send data at 56 – 500 Kbps; receive at 1.5 Mbps

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Connecting to the InternetModems Modems

28.8 Kbps takes 4 3/4 hours to download 6 minute video High-speed phone lines

ISDN line 1 hour to download 6 minute video

DSL line 11 minutes to download 6 minute video

Cable Modems Connects the PC to a cable-TV system

6 minutes to download a 6 minute video Satellite

18 minutes to download 6 minute video

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Connecting to the InternetWireless technology

Wi-Fi is a name for a set of wireless standards set by IEEE (IEEE 802.11 standards).

A wireless network uses radio waves, just like cell phones, televisions and radios do.

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Several standards: 802.11b Was the first version to reach the marketplace.

Transmits in the 2.4 GHz. It can handle up to 11 Mbps. It uses complimentary code keying (CCK) coding.

802.11g It is faster because it uses orthogonal frequency-division multiplexing (OFDM), a more efficient coding technique. Transmits at 2.4 GHz It can handle up to 54 Mbps.

802.11a It also and uses OFDM coding. Transmits at 5GHz and It can move up to 54 Mbps.

Newer standards, like 802.11n, can be even faster than 802.11g. However, the 802.11n standard isn't yet final.

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3G is the third generation of mobile phone standards and technology.

It is based on the International Telecommunication Union (ITU) family of standards under the International Mobile Telecommunications program, "IMT-2000".

Services include: Wide-area wireless voice telephony and Broadband wireless data, all in a mobile environment.

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3G vs. IEEE 802.11 networks IEEE 802.11 networks are short range, high-

bandwidth networks primarily developed for data.

3G networks are wide area cellular telephone networks which evolved to incorporate high-speed internet access and video telephony.

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Connecting to the InternetAccess Providers Internet Service Providers (ISP)

Local, regional, or national organization that provides internet access

Examples: AT&T Worldnet, EarthLink Commercial Online Service

A members-only company that provides specialized content and internet access

Examples: AOL, MSN

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Connecting to the InternetWireless Internet Service Providers

Internet Access for laptops, notebooks, smartphones, PDA users

These devices contain wireless modems

Examples: AT&T Wireless, Verizon Wireless, Earthlink Net Zero

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How Does the Internet Work?

The internet consists of thousands of smaller networks

These link educational, commercial, nonprofit, and military organizations

Most are Client/Server networks Client: a computer requesting

data or services Server or Host: a central

computer supplying data or services requested of it

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Point of Presence (POP) A local access point to

the internet A local gateway to the

ISP’s network

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Network Access Point (NAP) A routing computer at a point

on the internet where several connections come together

Owned by Network Service Providers (NSP)

Four major NAPs established in 1993 when the internet was privatized

Source of much internet congestion PNAPS

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Private/Peer NAPs (PNAP) Established in late 1990s Provide more backbone

access locations than the original 4 NAPs in Chicago, Washington D.C., New Jersey and San Francisco

>100 in U.S.A. at present Facilitate more efficient

routing since there are more backbone access locations

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Internet Backbone High-capacity,

high-speed data transmission lines

Use the newest technology

Providers include AT&T, Cable & Wireless, Sprint, Teleglobe, UUNET

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How Does the Internet Work?Protocol

The set of rules a computer follows to electronically transmit data.

Transmission Control Protocol/Internet Protocol (TCP/IP) is the internet protocol Developed in 1978 Used for all internet transactions

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How Does the Internet Work?Packets

Fixed-length blocks of data for transmission

Data transmissions are broken up into packets

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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 changes for each session Since addresses are limited, and most PCs are not

connected a lot of the time, dynamic addresses are common

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Who rules the Internet?

The board of trustees of the Internet Society (ISOC) oversees the infrastructure standards

Internet Corporation for Assigned Names and Numbers (ICANN) regulates domain names

American Registry for Internet Numbers (ARINN) administers the unique IP addresses for North & South America, Caribbean, and sub-Saharan Africa

Two other organizations administer the unique IP addresses for Europe and the Asia-Pacific region

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Internet 2 or UCAID (University Corporation for Advanced Internet Development)

A non-profit consortium which develops and deploys advanced network applications and technologies, for education and high-speed data transfer purposes.

New standards for large-scale higher-speed data transmission

It is led by 212 universities and partners with 60 companies in areas from the networking (Cisco Systems, Nortel and others), publishing (Prous Science) and technology industries such as Comcast, Intel and Sun Microsystems.

"Internet2" is a registered trademark Requires state-of-the-art infrastructure

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The World Wide Web

WWW was invented by Tim Berners-Lee 1989

Browsers 1990: First Web browser based on HTML

by Berners-Lee Early 1990s: Andreesen developed the

first graphical browser (Mosaic) Software for web-surfing Examples: Internet Explorer, Netscape

Navigator, Mozilla FireFox, Opera, Apple Macintosh browser

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The World Wide Web

Website The location on a particular computer

that has a unique address Example: www.barnesandnoble.com,

www.mcgraw-hill.com The website could be anywhere – not

necessarily at company headquarters

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The World Wide Web

Web Pages The documents and files on a company’s

website Can include text, pictures, sound, and

video Home page

The main entry point for the website Contains links to other pages on the

website

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The World Wide WebUniform Resource Locator (URL)

A character string that points to a specific piece of information anywhere on the web

A website’s unique address It consists of

The web protocol, http The domain name of the web server The directory or folder on that server The file within the directory, including

optional extension http://www.nps.gov/yose/home.html

protocol domain name file name . extensiondirectory

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The World Wide WebDomain names

Must be unique Identify the website, and the type of

site it is www.whitehouse.gov is NOT the same as

www.whitehouse.org .gov means government

.org means professional or nonprofit organization

Have you ever mistyped a URL and gone to a website you weren’t expecting? As we learn later in this chapter, some unscrupulous websites take advantage of this.

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The World Wide Web HTTP (HyperText Transfer Protocol)

Is the internet protocol used to access the World Wide Web

HTTPS is 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

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Web Browsers

Your tool for using the internet

Comes preinstalled on most PCs

5 basic elements Menu bar Toolbar URL bar Workspace Status bar

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Web Browsers

Home Page The page you see

when you open your web browser

You can change the Home Page on your browser

Back,Forward, Home & Search Use the menu bar

icons to move from one page to another

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Web BrowsersNavigation History Lists

A list of websites you visited since you opened up your browser for this session

Allows you to easily return to a particular site Bookmarks

Allows you to store the URL from a site on your PC so you can find it again in another browser session

To save the URL for a site, click on “Bookmark” in Internet Explorer or Mozilla Firefox

Or just type in the URL of the page you want to visit

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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

Most require you to log in, so you can Check the home page for general information Use the subject guide to find a topic you want Use a keyword to search for a topic

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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

If you publish an embarrassing web page and then take it down, is it REALLY gone?

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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

Metasearch Engines Specialized Search Engines

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4 web search tools Keyword Indexes Subject Directories 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

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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

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Should you trust 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?

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Email & Other Ways of Communicating over the Net Email program (email reader)

Enables you to send email by running email software on your computer that interacts with an email server at your ISP

Incoming mail is stored on the server in an electronic mailbox

Upon access, mail is sent to your client’s inbox

Examples: Microsoft’s Outlook Express, Netscape’s Mail, Apple Computer’s Apple Mail, QualComm’s Eudora

If your email is stored at the server and servers are backed up, when you delete an email is it gone for good?

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Email & Other Ways of Communicating over the Net Web-based Email

You send and receive messages by interacting via a browser with a website

Advantage: You can easily send and receive messages while traveling

Examples: Yahoo! Mail, Hotmail, Bluebottle, Sacmail

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Email & Other Ways of Communicating over the Net Using email

1. Get an email address, following the format [email protected]

2. Type addresses carefully, including capitalization, underscores, and periods

3. Use the reply command to avoid addressing mistakes

4. Use the address-book feature to store email addresses

5. Sort your email into folders or use filters

User Name Domain name

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Email & Other Ways of Communicating over the Net Email Attachments

A copy of a file or document that you send attached to an email to one or more people

Be careful about opening attachments Many viruses hide in them Know who is sending it to you before you open

it The recipient must have compatible

software to open the attachment. If they don’t have Excel, they probably can’t read the spreadsheet you sent them.

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Email & Other Ways of Communicating over the Net

Instant Messaging Any user on a given email system can send a

message and have it pop up instantly on the screen of anyone logged into that system

Examples: AOL Instant Messenger, MSN Messenger, ICQ, AT&T IM Anywhere, Yahoo Messenger

Not all IM systems interoperate To get it, you:

download the software connect to the internet register with the service

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FTP – File Transfer Protocol A software standard for transferring files

between computers with different Operating Systems Microsoft Windows Linux Unix Macintosh OS, and so forth

You can transfer files from an FTP site on the internet to your PC

Know your FTP site! If the FTP site is offering copyrighted material such

as music and movies for free, you are breaking US law if you download files!

You may also get a virus or spyware on your PC from them

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Newsgroups A giant electronic discussion board There are thousands of free internet

newsgroups Usenet is the worldwide public network of

servers on the internet www.usenet.com To participate you need a newsreader

Listserv An email-based discussion group Uses an automatic mailing-list server that

sends email to subscribers on selected topics

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Email & Other Ways of Communicating over the Net Real-Time Chat (RTC)

Participants have a typed discussion while online at the same time

This is not allowed in most college classrooms IM is one-on-one, but RTC has a list of

participants Netiquette – appropriate online behavior

Before you ask a question, consult the FAQ Avoid flaming Don’t SHOUT – use all capital letters Be careful with jokes Don’t send huge file attachments unless

requested

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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

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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 Applets

Small programs that can be quickly downloaded and run by most browsers

Java is the most common Applet language Microsoft’s Visual Studio creates ActiveX and com

objects

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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

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Webcasting and Blogs

RSS newsreaders Programs that scour the web and pull together

“feeds” from several websites to one place Blog

Short for web log, a diary-style web page Have become popular, both privately and in

politics Podcasting

Recording internet radio or similar internet audio programs

Some radio stations webcast their audio programs over the internet

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E-Commerce

Conducting business activities online B2B Commerce is business-to-business e-

commerce Online Finance now involves online banking, stock

trading online, and e-money such as PayPal Online auctions link buyers with sellers

eBay is the most well-known example of person-to-person auctions

OnSale is a vendor-based auction that buys merchandise and sells it at a discount

Priceline is an auction site for airline tickets and other items

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Snooping, Spoofing, Phishing, Pharming, Cookies, & Spyware

The internet was founded as a collaborative tool based on trust

Not everyone on the internet is honest Snooping

Email is not private Corporate management has the right to view

employees’ email Email that travels over the internet may be

captured and monitored and read by someone else

Not all ISPs protect their customers’ privacy

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Snooping, Spoofing, Phishing, Pharming, Cookies, & Spyware Spam: Electronic Junk Mail

Unsolicited email that takes up your time and may carry viruses or spyware

Delete it without opening the message Never reply to a spam message When you sign up for something, don’t give

your email address Use spam filters Fight back by reporting new spammers to

www.abuse.net or www.spamhaus.org or www.rahul.net/falk

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Snooping, Spoofing, Phishing, Pharming, Cookies, & Spyware

Spoofing Using fake email sender names so the message appears

to be from a different source, so you will trust it. If you don’t know the sender, don’t open it.

Phishing Using trusted institutional names to elicit confidential

information Some common schemes look like they are from your

bank or from eBay and ask you to “update” your account.

Don’t do it – the legitimate company already knows your account information!

If you want to update your information, CALL the number in the phone book, not the number in the email!

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Snooping, Spoofing, Phishing, Pharming, Cookies, & Spyware Pharming

Redirecting you to an imposter web page. Thieves implant malicious software on your PC Redirects you to an imposter web page even

when you type the correct URL! To foil it, type the URL with https first (for http

secure) https://www.microsoft.com Use this one with

https, not http://www.microsoft.com Since it has http, it

could be spoofed

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Snooping, Spoofing, Phishing, Pharming, Cookies, & Spyware Cookies

Little text files left on your hard disk by some websites you visit

Can include your log-in name, password, and browser preferences

Can be convenient But they can be used to gather

information about you and your browsing habits

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Snooping, Spoofing, Phishing, Pharming, Cookies, & Spyware Spyware

Applications that download without your knowledge

They hide on your PC and capture information about what is on the PC and what you are doing

That information is then transmitted to the spyware master’s website on the internet

Information may be used against you to steal your identity, get credit cards in your name, or for other crimes

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Snooping, Spoofing, Phishing, Pharming, Cookies, & Spyware Spyware (continued)

To prevent spyware, you must install and use “Antispyware software” at all times

Examples: Ad Aware, AntiSpyware, Spybot Search & Destroy, Pest Patrol, SpyCatcher, Yahoo toolbar with Anti-Spy

Be careful about free and illegal downloads since they are a source of spyware

Don’t say “I agree” when you are downloading something – read the fine print

Beware of unsolicited downloads

csce 101 introduction to computer concepts the internet & the world wide web chapter2

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