Bài giảng Using Information Technology 11e - Chapter 2: The Internet & the World Wide Web: Exploring Cyberspace

ChapterThe Internet & the World Wide Web: Exploring Cyberspace2Chapter 2 TopicsUNIT 2A: The Internet & the Web 2.1 Connecting to the Internet: Narrowband, Broadband, & Access Providers2.2 How Does the Internet Work? 2.3 The World Wide WebUNIT 2B: The Riches & Risks of Internet Use2.4 Email & Other Ways of Communicating over the Net2.5 The Online Gold Mine: Telephony, Multimedia, Webcasting, Blogs, E-Commerce, & Social Networking2.6 The Intrusive Internet: Snooping, Spamming, Spoofing, Phishing, Pharming, Cookies, & Spyware2UNIT 2A: The Internet & the WebThe Internet began in 1969 as ARPANET.The Internet was text-only. In the early 1990s, multimedia became available on the Internet, and the World Wide Web (web) was born.3This is the first image uploaded to the web, in 1992.To connect to the Internet you need1. An access device (computer with modem)2. A means of connection (phone line, cable hookup, or wireless)3. An Internet access provider2.1 Connecting to the InternetNarrowband, Broadband, & Access Providers5However you connect to the Internet, the bandwidth will determine the speed of your connection.Bandwidth: Expresses how much data can be sent through a communications channel in a given amount of time.Baseband: Slow type of connection that allows only one signal to be transmitted at a time.Broadband: High-speed connections.6Physical connection to Internet—wired or wireless?Telephone [dial-up] modemHigh-speed phone line—DSL, T1/T3Cable modemWireless—satellite and other through-the-air links7Data Transmission SpeedsOriginally measured in bits per second (bps) 8 bits are needed to send one character, such as A or aKbps connections send 1 thousand bits per secondMbps connections send 1 million bits per secondGbps connections send 1 billion bits per secondUploading & DownloadingUpload—transmit data from local to remote computerDownload—transmit data from remote to local computer8Narrowband (Dial-Up Modem): Low speed but inexpensiveTelephone line = narrowband, or low bandwidth, low speedDial-up connection—use of telephone modem to connect to Internet (used mostly in rural areas on POTS, or plain old telephone system)Telephone ModemsCan be either internal or externalMaximum speed of 56 KbpsMost ISPs offer local access numbers9Telephone (Dial-Up) Modem10Panel 2.3Page 55High-Speed Phone LinesMore expensive but available in cities & most townsDSL lineUses regular phone lines, DSL modemReceives data at 7 ̶ 105Mbps; sends at about 384 Kbps – 1 MbpsIs always onNeed to live no farther than 4.5 miles from phone company switching officeNot always available in rural areasT1 line—very expensiveTraditional trunk line, fiber optic or copper; carries 24 normal telephone circuitsTransmission rate of 1.5 ̶ 6 Mbps (T3 = 6 – 47 Mbps)The “last mile” can still be a problemGenerally used by large organizations11High-Speed Phone LinesCable modemTV cable system with Internet connection; company usually supplies cable modemIs always onReceives data at up to 100 Mbps; sends at about 2-8 Mbps12Basic DSL/Cable-PC systemPanel 2.4Page 57Satellite Wireless ConnectionsTransmits data between satellite dish and satellite orbiting earthConnection is always onRequires Internet access provider with 2-way satellite transmissionUser needs to buy or lease satellite dish and modem and have them connected14Other Wireless: Wi-Fi, 3G, & 4GWi-Fi—stands for “wireless fidelity” Name for a set of wireless standards (802.11) set by IEEETransmits data wirelessly up to 54 Mbps for 300 – 500 feet from access point (hotspot)Typically used with laptops and tablets that have Wi-Fi hardware3G = “third generation”; uses existing cellphone system; handles voice, email, multimedia4G = “fourth generation”; faster than 3G; built specifically for Internet traffic – but not standard yetBoth 3G and 4G used mostly in smartphones15Internet Access Providers (ISPs)ISP: Local, regional, or national organization that provides access to the Internet for a fee — e.g., Comcast, Charter, AT&T.Wireless Internet Service Provider (WISP) — e.g., AT&T, T-Mobile, Verizon Wireless, Sprint, CredoEnables wireless-equipped laptop/tablet and smartphone users to access Internet162.2 How Does the Internet Work?17The Internet is basically a huge network that connects hundreds of thousands of smaller networks.Central to this arrangement are client/server networksClient: computer requesting data or servicesServer or host computer: central computer supplying data or services requested of it18ClientPoint of Presence (POP)A collection of modems and other equipment in a local areaA local gateway (access) to an ISP’s networkISP connects to an IXPInternet Exchange Point (IXP)A routing computer at a point on the Internet where several connections come togetherIXPs are run by private companiesAllow different ISPs to exchange Internet traffic19(continued)Internet Connections: POP & IXPsInternet BackboneHigh-speed, high-capacity data transmission lines, usually fiber optic Uses the newest technologyProviders include AT&T, Sprint, Verizon, CenturyLink, and Deutsche TelekomInternet 2Cooperative university/business education and research projectAdds new “toll lanes” to older Internet to speed things upAdvances videoconferencing, research, collaboration20Internet Connections: Backbone, & Internet221Panel 2.5Page 59How the Internet worksInternet Communications: Protocols, Packets, & IP AddressesHandshaking & Authentication: Connecting to your ISP’s point of presence (POP)Handshaking—fastest transmission speed establishedAuthentication—correct password & user nameProtocolsThe set of rules a computer follows to electronically transmit data.TCP/IP (Transmission Control Protocol/Internet Protocol) is the Internet protocolDeveloped in 1978 by ARPA; used for all Internet transactionsPacketsFixed-length blocks of data for transmission, determined by TCP/IPData transmissions are broken up into packets and re-assembled at destination (the IP—Internet Protocol— address)22Every device connected to the Internet has an addressEach IP address uniquely identifies that deviceThe address is four sets of numbers separated by periods (e.g., 1.160.10.240)Each number is between 0 and 255Dynamic IP addresses change with every use; individual computer users are assigned static IP addresses when they log onStatic IP addresses don’t change (established organizations – including ISPs – and companies have static IP addresses, which they pay for)23IP (Internet Protocol) AddressesWho Runs the Internet?Basically, no one owns the InternetThe board of trustees of the Internet Society (ISOC) oversees the standardsInternet Corporation for Assigned Names and Numbers (ICANN) regulates domain names (such as .com, edu., .net) that overlie IP addresses; ICANN does not control content242.3 The World Wide Web25The Face of the Web: Browsers, Websites, & Web PagesThe World Wide Web brought multimedia to the Internet.The web and the Internet are not the same; the web is multimedia-based, and the Internet is not. The Internet is the infrastructure that supports the web.A browser is software that gets you to websites and their individual web pages and displays the content in such a way that the content appears mostly the same regardless of the computer, operating system, and display monitor.Examples = Internet Explorer Mozilla FireFox Apple Macintosh’s Safari Google’s Chrome Microsoft’s Bing26WebsiteThe location on a particular computer (server) that has a unique address; example = www.barnesandnoble.com, www.mcgraw-hill.comThe website (server) could be anywhere — not necessarily at company headquartersWeb PageA document on the web that can include text, pictures, sound, and videoThe first page on a website is the Home pageThe Home page contains links to other pages on the website (and often other websites)27Uniform Resource Locator (URL): address for a web pageA character string that points to a specific piece of information anywhere on the webA website’s unique addressIt consists ofThe web protocol, domain name of the web serverThe directory name or folder on that serverThe file within the directory, including optional extension28How the Browser Finds Thing: URLsTCP/IP— As explained (p. 60), general Internet ProtocolHTTP—Protocol Used to Access World Wide WebHypertext Markup Language (HTML)The “markup” language used in writing and publishing web pagesSet of instructions used to specify document structure, formatting, and links to other documents on the webHypertext links connect one web document to another29The Nuts & Bolts of the Web: HTML & HyperlinksTim Berners-Lee saw the possibility of using hyperlinks to link any information to any other information over the Internet.hypertext linkWeb browsers interpret HTML and allow you to move around the Internet and the webCome preinstalled on most PCs, but you can download others5 basic elementsURL (address)barMenu barToolbarWorkspaceStatus bar (displays current status of the web age; 100% = fully loaded)30Using Your Browser to Get around the WebBrowser’s Home PageThe page you see when you open your web browserYou can change the Home Page on your browserBack, Forward, HomeUse the browser’s icons to move from one page to another (these icons can appear on different bars in different browsers)31NavigationHistory ListA list of websites you visited since you opened up your browser for this sessionAllows you to easily return to a particular siteBookmarkAllows you to store the URL from a site on your computer so you can find it again in another browser sessionTo save the URL for a site, click on “Favorites” in Internet Explorer, “Bookmarks” in Mozilla Firefox, or the star icon in the URL address bar in Chrome32Interactivity with a web pageClick on hyperlinks to transfer to another pageClick on a radio button to choose an optionType text in a text box and then hit EnterClick on scroll arrows to move up and down, or side to side, on a pageClick on different frames (separate controllable sections of a web page)33Web portals: Starting points for finding informationA portal is 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 categoriesExamples: Yahoo!, Google, Bing, Lycos, and AOLMost require you to log in, so you canCheck the Home page for general informationUse the subject guide to find a topic you wantUse a keyword to search for a topic34Search Services & Search EnginesOrganizations that maintain databases accessible through websites to help you find information on the internetExamples: portals like Yahoo! and Bing, plus Google, Ask.com, GigablastSearch services maintain search engines—programs that users can use to ask questions or use keywords to find informationDatabases of search engines are compiled using software programs called spiders (crawler, bots, agents)Spiders crawl through the World Wide WebFollow links from one page to anotherIndex the words on that siteA search never covers the entire webSearch engines differ in what they cover351. Individual Search EnginesCompile their own searchable databases on the webYou search by typing keywords and receiving “hits”Examples are Ask, Bing, Google, and Yahoo!2. Subject DirectoriesCreated and maintained by human editors, not electronic spidersAllow you to search for information by selecting lists of categories or topicsExample sites are Beaucoup!, LookSmart, Open Directory Project, and Yahoo! Directory36(continued)Four Web Search Tools3. Metasearch EnginesAllows you to search several search engines simultaneouslyExamples are Yippy!, Dogpile, Mamma, MetaCrawler, and Webcrawler4. Specialized Search EnginesHelp locate specialized subject matter, such as info on movies, health, jobsExamples are Career.com. WebMD, Expedia, U.S. Census Bureau37Smart Searching: Three General StrategiesIf you’re just browsing . . .Try a subject directoryNext try a metasearch engineIf you’re looking for specific information . . .Try a Answers.com “one-click” searchOr go to a general search engine, then a specialized oneIf you’re looking for everything on a subject . . .Try the same search on several search engines38Wikis & WikipediaA wiki is a simple piece of software that can be downloaded for free and used to make a website (also called a wiki) that can be corrected or added to by anyone. Wikipedia is a free online encyclopedia that anyone around the world can contribute to or edit. It has more than 25 million articles in more than 285 languages; over 4.1 million articles appear in the English Wikipedia alone. However, Wikipedia is not considered reliable or authoritative by many academics and librarians.Still images—e.g., Google Image Search, Bing Images, Fagan FinderAudio—e.g., Yahoo! Music, Lycos MP3 SearchVideo—e.g., AlltheWeb, AOL.videoScholarly—e.g., Google Scholar40Multimedia Search ToolsTags: Do-it-yourself labels that people can put on anything found on the Internet, from articles to photos to videos, that help them to find their favorite sites again and to link them.Can be shared easily with other peopleTags are commonly used on blogs and YouTube – word listed at the bottom. Essentially tags are keywords used to classify content.  (The # is a hash symbol; thus the Twitter term hashtag. )Tag managing is available through delicious.com and BlinkList, among other companies.41TaggingUNIT 2B: The Riches & Risks of Internet Use422.4 Email, Instant Messaging, & Other Ways of Communicating over the Net43EmailOutgoing mail: sent from your computer to a Simple Mail Transfer Protocol (SMTP) server run by your ISPIncoming mail: Email sent to your computer: uses Post Office Protocol version 3 (POP3)4445Page 77 Two ways to send & receive email:1. Email ProgramEnables you to send email by running email software on your computer that interacts with an email server at your Internet access providerIncoming mail is stored on the server in an electronic mailboxUpon access (your ID and password), mail is sent to your software’s inboxExamples: Microsoft Outlook, Apple Mail 2. Web-Based EmailYou send and receive messages by interacting via a browser with a websiteAdvantage: You can easily send and receive messages while traveling, using any computer or equipped mobile deviceExamples: Yahoo! Mail and Gmail (Google)Disadvantages are ads and email hacking46Using email Get an email address from your ISP, following this format:47Tips for Using Email1. Use the address-book feature to store email addresses2. Use folders to organize email3. Be careful with attachments4. Be aware of email netiquette 48Email AttachmentsA copy of a file or document that you send attached to an email to one or more peopleRecipients must have compatible software to open the attachment; for example, if they don’t have Excel, they probably can’t read the spreadsheet you sent them.Be careful about opening attachments:Many viruses hide in them; scan them with antivirus softwareKnow who has sent the attachment before you open it49Netiquette: Appropriate Online BehaviorDon’t waste people’s time.Don’t write anything that you would not say to a person’s face.Include helpful subject and signature lines.Be clear and concise.Avoid spelling and grammatical errors.Avoid SHOUTING and flaming.Also:Be careful with jokes.Avoid sloppiness, but avoid criticizing other’s sloppiness.Don’t send huge file attachments unless requested.When replying, quote only the relevant portion.Don’t overforward (don’t copy emails to everyone you know).50Instant MessagingInstant messaging enables you to communicate by email with specified other users (“buddies”) in real time.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.To get IM: Download IM software from a supplierExamples: AOL/AIM, Google Chat, Windows Messenger, Yahoo! MessengerDone on computers; is not the same as texting.51Discussion GroupsMailing Lists:One-way (to make announcements) or two-way (for discussions) email subscription listsEmail discussion groups on special-interest topics, in which all subscribers receive email messages sent to the group’s email addressNewsgroups:Giant electronic bulletin board for written discussions about specific subjectsTo participate you need a newsreader programMessage Boards:Special-interest discussion groups without newsreadersAccessed through a web browserA collection of messages on a particular topic is called a thread 52FTP (File Transfer Protocol)Software standard for transferring large files between computers, including those with different operating systemsYou can also transfer files from an FTP site on the Internet to your PCFTP sites offer many free filesFTP sites may be either public or proprietaryYou can download using your web browser or FTP client programs, such as Fetch, Cute, FileZilla, and SmartFTP532.5 The Online Gold MineTelephony, Multimedia, Webcasting, Blogs, E-Commerce, & Social NetworkingTelephony: The Internet TelephoneUses the Internet to make phone calls via VoIP (Voice over Internet Protocol)Long-distance calls are either very inexpensive or freeWith no PC, dial a special phone number to packetize your call for a standard telephoneUse with a PC that has a sound card, microphone, Internet connection with modem & ISP, and internet telephone software such as Skype and VonageAlso allows videoconferencing55Multimedia on the WebAllows you to get images, sound, video, and animationMay require a plug-in, player, or viewerA downloadable program that adds a specific feature to a browser so it can view certain filesExamples: Flash, RealPlayer, QuickTimeMultimedia AppletsSmall programs that can be quickly downloaded and run by most browsersJava is the most common Applet languageText & Images: great variety availableExample: Google Earth56(continued)AnimationThe rapid sequencing of still images to create the appearance of motionUsed in video games and web images that seem to move, such as bannersVideo & AudioDownloaded completely before the file can be played, orDownloaded as streaming video/audioExamples: RealVideo and RealAudio57The Web Automatically Comes to YouPush technology: Software that automatically downloads information to personal computers.Webcasting: Sending users customized text, video, audio on regular basis.RSS newsreaders (RSS aggregators): Programs that scour the web, sometimes hourly, sometimes more frequently, and pull together in one place “feeds” from several websites. RSS is based on XML, or extensible markup language, a web-document tagging and formatting language that is an advance over HTML and that two computers can use to exchange information.58XML and RSS have led to blogs and blogosphere.Blogs (weblogs) are frequently updated sites on the web intended for public consumption that contain a writer’s observations, opinions, images, and links to other websites.Podcasting: Internet radio or similar Internet audio program delivered via RSS feed to a subscriber to be played back on computer or digital audio device.59E-Commerce: B2B, B2C, & C2CE-Commerce (electronic commerce): conducting business activities onlineE-commerce has led to showrooming, the phenomenon in which shoppers browse for products in stores, only to buy them from an online rival, frequently at a lower price.B2B is business-to-business e-commerce.Business-to-consumer commerce, or B2C, is the electronic sale or exchange of goods and services from the companies directly to the public, or end users (e.g., online banking, online shopping, online stock trading).Consumer-to-consumer commerce, or C2C, is the electronic sale or exchange of goods and services between individuals (e.g., auctions).60Discussion Question: Have you every sold anything on eBay? Used PayPal? Did you have any problems? What would you warn people about?Web 2.0: The Social Web Web 2.0 refers to the web viewed as a medium in which interactive experience, in the form of blogs, wikis, forums, social networking, and so on, plays a more important role than simply accessing information.The move toward a more social, collaborative, interactive, and responsive web; has led to the “social web,” giving rise to:Social networking sites: Online communities that allow members to keep track of friends and share photos, videos, music, stories, and ideas (e.g., Facebook, LinkedIn).Media-sharing sites: Online social networks in which members share media such as photos, videos, music, ideas (e.g., YouTube, Flicker, Shutterfly).Social-network aggregators: Collect content from all of a user’s various social network profiles into one place, then allow him or her to track friends and share other social network activities (e.g., Mugshot, Readr).61In Web 3.0, information will be computer-generated with less human interaction required to discover and integrate that information.Two ideas might form the basis for Web 3.0— semantic markup and a personal browser.Semantic markup: Data interchange formats that will allow machines to understand the meaning—or “semantics”—of information on the web.The Web 3.0 browser will probably act as a personal assistant because every user will have a unique Internet profile based on his or her browsing history. The more you use the Web, the more your browser learns about you and the less specific you'll need to be with your questions.62Web 3.0: Computer-Generated Information 2.6 The Intrusive InternetSnooping, Spamming, Spoofing, Phishing, Pharming, Cookies, Spyware, & MalwareSnoopingEmail is not privateCorporate management has the right to view employees’ email.Friends can send email anywhere.Not all ISPs protect their customers’ privacy.Deleted emails can be retrieved from a hard disk.64Spam: Electronic Junk MailUnsolicited email that takes up your time.Delete it without opening the message.Never reply to a spam message.Do not click on “unsubscribe” at the bottom of an email.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. 65SpoofingUsing 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.PhishingSending forged email directing recipient to fake website.Purpose: to entice people to share personal or financial data.Fake website looks like real website, such as a bank’s.PharmingImplanting malicious software on a victim’s computer that redirects the user to an impostor web page even when the individual types the correct address into his or her browser.Use websites with URLs that begin with “https://Some spyware removal programs can correct the corruption.6667Phishing examples"YOUR NET ID ACCOUNT" Phishing Scam (3/31/2013)https://wiki.library.ucsb.edu/display/SYSPUB/Latest+Phishing+AttemptsPhishing Examples Little text files left on your hard disk by some websites you visit.Can include your log-in name, password, browser preferences, and credit card information.Every time you load a particular website, the browser sends the cookie back to the server to notify the website of your previous activity.Can make visiting these websites next time more convenient and faster.But cookies can be used to gather information about you and your browsing habits and history; this information can be used without your consent.A first-party cookie is a cookie from a website that you have visited. Third-party cookies are placed by trusted partners of the websites you visit. (Third-party cookies are frequently placed by ad networks.)68Cookies Spyware is software surreptitiously installed on your computer via the web.Spyware hides on your PC/device and captures information about what is on the it, such as keystrokes and passwords69Spyware : Adware, Browser & Search Hijackers, & Key LoggersAdware, or pop-up generator, is a kind of spyware that tracks web surfing or online buying so that marketers can send you targeted and unsolicited pop-up and other ads.Browser hijackers change settings in your browser without your knowledge, often changing your browser’s home page and replacing it with another web page. Search hijackers intercept your legitimate search requests made to real search engines and return results from phony search services designed to send you to sites they run.Key loggers, or keystroke loggers, can record each character you type and transmit that information to someone else on the Internet, making it possible for strangers to learn your passwords and other information.MalwareThere are many forms of malicious software—so-called malware—that can harm a computer system, a common danger being viruses.A virus is a rogue program that migrates through the Internet or via operating systems and attaches itself to different programs that spread from one computer to another, leaving infections.The principal defense is to install antivirus software, which scans a computer to detect viruses and, sometimes, to destroy them.How to Reduce Malware RisksDownload virus protection software, such as McAfee VirusScan ( www.mcafee.com ) or Norton AntiVirus ( www.symantec.com/nav ); then follow instructions for installing it on your machine. (Don’t use antivirus software from companies you know nothing about.) Scan your entire system with antivirus software the first time it’s installed; then scan it regularly after that. Also scan any new CDs and drives before using them.Don’t open, download, or execute any files, email messages, or email attachments if the source is unknown or if the subject line of an email is questionable or unexpected.Delete all spam and email messages from strangers. Don’t open, forward, or reply to such messages.Use webmail sparingly, since viruses can hide in the HTML coding of the email. Eventhe simple act of previewing the message in your email program can activate the virusand infect your computer.Don’t start your computer with a flash drive, USB thumb drive, or CD/DVD in place.Back up your data files regularly, and keep at least one backup device in a location separate from your computer or use an online (cloud) backup service.If you discover you have a virus, ask McAfee or Norton to scan your computer online; then follow its directions for cleaning or deleting the virus. (A computer tech person can do this, too.)PasswordsNever choose a real word or variations of your or your family’s name, address, phone number, Social Security number, license plate, or birth date.Don’t use passwords that can be easily guessed, such as “12345” or “password.”Avoid any word that appears in a dictionary. Instead, mix letters, numbers, and punctuation marks in an oddball sequence of no fewer than eight characters, such as 2b/orNOT2b% and Alfred!E!Newman7. Or choose a password that is memorable but shift the position of your fingers on the keyboard, so that, for instance, TIMBERWOLVES becomes YO,NRTEP;BRD when you move your fingers one position right. For sensitive sites, such as financial accounts, create long passwords, such as 15-character passwords.Don’t use the same password for multiple sites, so that if someone obtains the password to one account, that person won’t have access to your entire online life.Don’t write passwords on sticky notes or in a notebook or tape them under your keyboard. Don’t carry the passwords in your wallet. If you have to write down all your passwords, find a safe place to put the paper, or use a software password manager, such as Kaspersky Password Manager, RoboForm Everywhere, or Last Pass Premium.