User:Salman.haider22
Chapter No: 02 THE INTERNET & THE WORLD WIDE WEB Exploring Cyberspace
Chapter Topics 2.1 Connecting to the Internet: Narrowband, Broadband, & Access Providers 2.2 How Does the Internet Work? 2.3 The World Wide Web 2.4 Email & Other Ways of Communicating over the Net 2.5 The Online Gold Mine: Telephony, Multimedia, Webcasting, Blogs, E-Commerce, & Social Networking 2.6 The Intrusive Internet: Snooping, Spamming, Spoofing, Phishing, Pharming, Cookies, & Spyware
2.1 Connecting to the Internet Narrowband, Broadband, & Access Providers
Internet history
1. Began with 1969s ARPANET for U.S. Dept. of Defense 2. 62 computers in 1974 3. 500 computers in 1983 4. 28,000 computers in 1987 5. Early 1990s, multimedia became available on Internet 6. 2010 = about 2 billion people on Internet
To connect you need
1. An access device (computer with modem) 2. A means of connection (phone line, cable hookup, or wireless) 3. An Internet access provider
DEFINITION: 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. DEFINITION: Baseband is a slow type of connection that allows only one signal to be transmitted at a time. DEFINITION: Broadband is a high-speed connection that allows several signals to be transmitted at once.
Physical connection to Internet—wired or wireless
1. Telephone [dial-up] modem 2. High-speed phone line—DSL, T1/T3 3. Cable modem 4. Wireless—satellite and other through-the-air links
Data Transmission Speeds
1. Originally measured in bits per second (bps) 2. 8 bits are needed to send one character, such as A or a 3. Kbps connections send 1 thousand bits per second 4. Mbps connections send 1 million bits per second 5. Gbps connections send 1 billion bits per second
Uploading & Downloading
1. Upload—transmit data from local to remote computer 2. Download—transmit data from remote to local computer
Narrowband (Dial-Up Modem)
1. Telephone line = narrowband, or low bandwidth, low speed 2. Dial-up connection—use of telephone modem to connect to Internet (used mostly in rural areas)
Telephone Modems
1. Can be either internal or external 2. Most ISPs offer local access numbers
Telephone (Dial-Up) Modem
High-Speed Phone Lines DSL line 1. Uses regular phone lines, DSL modem 2. Receives data at 1.5 ̶ 10 Mbps; sends at 128 Kbps – 1.5 Mbps 3. Need to live no farther than 3 miles from phone company switching office 4. Not always available in rural areas
T1 line—very expensive
1. Traditional trunk line; carries 24 normal telephone circuits 2. Transmission rate of 1.5 ̶ 6 Mbps (T3 = 6 – 45 Mbps)
Cable modem
1. TV cable system with Internet connection; company usually supplies cable modem 2. Receives data at up to 30 Mbps; sends at about 1.4 Mbps Satellite Wireless 1. Transmits data between satellite dish and satellite orbiting earth 2. Sends data at around 200 ̶ 512 Kbps; receives at 1 ̶ 5 Mbps 3. Connection is always on 4. Requires Internet access provider with 2-way satellite transmission 5. User needs to buy or lease satellite dish and modem and have them connected
Other Wireless
Wi-Fi & 3G/4G Wi-Fi—stands for “wireless fidelity”
1. Name for a set of wireless standards (802.11) set by IEEE 2. Transmits data wirelessly up to 54 Mbps for 300 – 500 feet from access point (hotspot) 3. Typically used with laptops and tablets that have Wi-Fi hardware
3G—stands for “third generation”; 4G = “fourth generation”
1. High-speed wireless that does not need access points, because it uses existing cellphone system 2. Used mostly in smartphones 3. Can deliver downloadable video clips, hi-res games; has Internet access, handles phone calls and email Internet Access Providers
Three Types
1. Internet Service Provider (ISP) — e.g., Earthlink and Comcast
Company that links online users to its servers, which link users to the Internet through another company’s network
2. Commercial Online Service — e.g., AOL and MSN
Members-only company that provides specialized content as well as Internet access
3. Wireless Internet Service Provider (WISP) — e.g., AT&T, Cingular, Verizon
Enables wireless-equipped laptop/tablet and smartphone users to access Internet
2.2 How Does the Internet Work?
The Internet consists of hundreds of thousands of smaller networks Central to this arrangement are client/server networks
1. Client: computer requesting data or services 2. Server or host computer: central computer supplying data or services requested of it Internet Connections POP, IXPs, Backbone, & Internet2
Point of Presence (POP)
1. A collection of modems and other equipment in a local area 2. A local gateway to an ISP’s network 3. ISP connects to an IXP
Internet Exchange Point (IXP)
1. A routing computer at a point on the Internet where several connections come together 2. IXPs are run by private companies
Internet connections continued Internet Backbone 1. High-speed, high-capacity data transmission lines, usually fiber optic 2. Uses the newest technology 3. Providers include AT&T, Sprint, Verizon, Qwest, and Deutsche Telekom Internet 2 1. Cooperative university/business education and research project 2. Adds new “toll lanes” to older Internet to speed things up 3. Advances videoconferencing, research, collaboration
Internet Communications
Handshaking & Authentication: Connecting Your Modem to ISP
1. Handshaking—fastest transmission speed established 2. Authentication—correct password & user name
Protocols
1. The set of rules a computer follows to electronically transmit data. 2. TCP/IP (Transmission Control Protocol/Internet Protocol) is the Internet protocol 3. Developed in 1978 by ARPA; used for all Internet transactions
Packets
1. Fixed-length blocks of data for transmission 2. Data transmissions are broken up into packets and re-assembled at destination (the IP—Internet Protocol— address) IP Addresses
Every device connected to the Internet has an address Each IP address uniquely identifies that device The address is four sets of numbers separated by periods (e.g.,1.160.10.240) Each number is between 0 and 255 Dynamic IP addresses change with every use; individual computer users are assigned static IP addresses when they log on Static IP addresses don’t change (established organizations – including ISPs – and companies have static IP addresses, which they pay for)
Who Runs the Internet?
Basically, no one owns the Internet The board of trustees of the Internet Society (ISOC) oversees the standards Internet Corporation for Assigned Names and Numbers (ICANN) regulates domain names (such as .com, edu., .net) that overlie IP addresses; ICANN does not control content
2.3 The World Wide Web Browsers, Websites, & Web Pages
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.
Browsers
Software for web surfing (for accessing particular servers on the Internet); examples = Internet Explorer
Mozilla FireFox
Apple Macintosh’s Safari
Google’s Chrome
Microsoft’s Bing
Website
1. The location on a particular computer (server) that has a unique address; example=www.barnesandnoble.com, www.mcgraw-hill.com 2. The website (server) could be anywhere — not necessarily at company headquarters
Web Page
1. A document on the web that can include text, pictures, sound, and video 2. The first page on a website is the Home page 3. The Home page contains links to other pages on the website (and often other websites)
Uniform 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
1. The web protocol, http:// 2. The domain name of the web server 3. The directory name or folder on that server 4. The file within the directory, including optional extension
TCP/IP— As explained, general Internet Protocol HTTP—Protocol Used to Access World Wide Web Hypertext Markup Language (HTML)
The “markup” language used in writing and publishing web pages Set of instructions used to specify document structure, formatting, and links to other documents on the web
Hypertext links connect one web document to another
Web browsers interpret HTML and allow you to move around the Internet and the web Come preinstalled on most PCs, but you can download others 5 basic elements
1. URL (address)bar 2. Menu bar 3. Toolbar 4. Status bar 5. Workspace
Browser’s Home Page
1. The page you see when you open your web browser 2. You can change the Home Page on your browser
Back, Forward, Home
1. Use the menu bar icons to move from one page to another
Navigation History Lists
1. A list of websites you visited since you opened up your browser for this session 2. Allows you to easily return to a particular site
Navigation Bookmarks
1. Allows you to store the URL from a site on your computer so you can find it again in another browser session 2. To save the URL for a site, click on “Favorites” in Internet Explorer or Bookmarks” Mozilla Firefox
Interactivity with a web page
1. Click on hyperlinks to transfer to another page 2. Click on a radio button to choose an option 3. Type text in a textbox and then hit Enter 4. Click on scroll arrows to move up and down,or side to side, on a page 5. Click on different frames (separate controllable sections of a web page)
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!, Google, Bing, Lycos, and AOL Most require you to log in, so you can
1. Check the Home page for general information 2. Use the subject guide to find a topic you want 3. Use a keyword to search for a topic Search Services & Search Engines
Organizations that maintain databases accessible through websites to help you find information on the internet Examples: portals like Yahoo! and Bing, plus Google, Ask.com, Gigablast Search services maintain search engines—programs that users can use to ask questions or use keywords to find information Databases of search engines are compiled using software programs called spiders (crawler, bots, agents)
1. Spiders crawl through the World Wide Web 2. Follow links from one page to another 3. Index the words on that site 4. A search never covers the entire web 5. Search engines differ in what they cover
Four Web Search Tools
1. Individual Search Engines Compile their own searchable databases on the web You search by typing keywords and receiving “hits” Examples are Ask, Bing, Google, and Yahoo! 2. Subject Directories Created and maintained by human editors, not electronic spiders Allow you to search for information by selecting lists of categories or topics Example sites are Beaucoup!, Galaxy, Google Directory, LookSmart, Open Directory Project, and Yahoo! Directory 3. Metasearch Engines Allows you to search several search engines simultaneously Examples are Yippy!, Dogpile, Mamma, MetaCrawler, and Webcrawler 4. Specialized Search Engines Help locate specialized subject matter, such as info on movies, health, jobs Examples are Career.com. WebMD, Expedia, U.S. Census Bureau
Smart Searching: Three General Strategies If you’re just browsing . . .
1. Try a subject directory 2. Next try a metasearch engine
If you’re looking for specific information . . .
1. Try a Answers.com “one-click” search 2. Or go to a general search engine, then a specialized one
If you’re looking for everything on a subject . . .
1. Try the same search on several search engines
Multimedia Search Tools
1. Still images—e.g., Google Image Search 2. Audio—e.g., Yahoo! Music 3. Video—e.g., AllTheWeb 4. Scholarly—e.g., Google Scholar
Desktop Search
1. Desktop search engine: a tool that extends searching beyond the web to the contents of your computer’s hard disk 2. Uses technology similar to that in web search engines 3. Offered by all of the principal search engine services as a download
Tagging
1. Tags: do-it-yourself labels that people can put on anything found on the internet, from articles to photos to videos 2. Can be shared easily with other people 3. Tags are available through delicious.com, BlinkList, Flickr 2.4 Email & Other Internet Communication Email
Outgoing mail: sent from your computer to a Simple Mail Transfer Protocol (SMTP) server run by your ISP Incoming mail: Email sent to your computer: uses Post Office Protocol version 3 (POP3)
Two ways to send & receive email:
1. Email Program 1. Enables you to send email by running email software on your computer that interacts with an email server at your Internet access provider 2. Incoming mail is stored on the server in an electronic mailbox 3. Upon access (your ID and password), mail is sent to your software’s inbox 4. Examples: Microsoft Outlook, Apple Mail 2.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, using any computer or equipped mobile device Examples: Yahoo! Mail, Windows Live Hotmail, Gmail (Google), and AOL Mail Using email
Get an email address from your ISP, following the format:
Tips for Using Email
1. Type addresses carefully, including capitalization, underscores, and periods 2. Use the reply command to avoid addressing mistakes 3. Use the address-book feature to store email addresses 4. Deal with each email only once 5. Don’t “bloat” your email 6. Use folders to organize email
Email Attachments A copy of a file or document that you send attached to an email to one or more people 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. Be careful about opening attachments:
1. Many viruses hide in them; scan it with antivirus software 2. Know who is sending it to you before you open it
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 To get IM: download IM software from a supplier Examples: AOL/AIM, Google Talk, MySpace, Facebook, and Yahoo! Messenger Downside of IM: Lack of privacy Time wasters FTP (File Transfer Protocol) Software standard for transferring large files between computers, including those with different operating systems You can also transfer files from an FTP site on the Internet to your PC FTP sites offer many free files FTP sites may be either public or proprietary You can download using your web browser or FTP client programs, such as Fetch, Cute, and SmartFTP
Newsgroups / ListServ 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 Netiquette Appropriate Online Behavior Before you ask a question, consult the FAQs Avoid flaming Don’t SHOUT – use all capital letters 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”
2.5 The Online Gold Mine
Internet Telephony Uses the Internet to make phone calls via VoIP (Voice over Internet Protocol) Long-distance calls are either very inexpensive or free With no PC, dial a special phone number to packetize your call for a standard telephone With a PC that has a sound card, microphone, Internet connection with modem & ISP, and internet telephone software such as Skype and Vonage Also allows videoconferencing Multimedia on the Web Allows you to get images, sound, video, and animation May require a plug-in, player, or viewer A downloadable program that adds a specific feature to a browser so it can view certain files Examples: RealPlayer, QuickTime Multimedia Applets Small programs that can be quickly downloaded and run by most browsers Java is the most common Applet language Text & Images: great variety available
1. Example: Google Earth
Animation The rapid sequencing of still images to create the appearance of motion Used in video games and web images that seem to move, such as banners Video Streaming video transfers data in a continuous flow so you can begin viewing a file before it is all sent Example is RealPlayer Audio may be transmitted either: Downloaded completely before the file can be played, or Downloaded as streaming audio
Push Technology & Webcasting Push technology, software that automatically downloads information to personal computers Webcasting is sending users customized text, video, audio on regular basis
RSS, XML, Blogging, & Podcasting RSS newsreaders: programs that scour the web and pull together in one place “feeds” from several websites Based on XML (extensible markup language): a web-document tagging and formatting language XML and RSS have led to blogs and bologosphere Blog: short for web log, a diary-style web page; can include multimedia 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 E-Commerce E-Commerce (electronic commerce): conducting business activities online
1. B2B commerce is business-to-business e-commerce 2. Online finance involves online banking, stock trading online, and e-money such as PayPal 3. Online auctions link buyers with sellers (e.g., eBay) 4. Online job hunting match job hunters with employers
Web 2.0 The move toward a more social, collaborative, interactive, and responsive web; has led to the “social web,” giving rise to: Social networking sites: Facebook, MySpace Social networking website: an online community that allows members to:
1. Keep track of friends 2. Share photos, videos, music, stories, and ideas
Media-sharing sites: YouTube, Flicker, Shutterfly, etc. Media-sharing website: type of online social network in which members share media such as photos, videos, music, ideas, and so forth Friendfeed, Spokeo, & other social-network aggregators
1. 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., FriendFeed, Readr)
Twitter & Tumbler & microblogging services
1. “Thoughtcasting” or “microblogging”: sending a text message from your mobile phone to friends’ web/IM or their phones 2. Called microblogging because messages must be short: 140 characters 3. Tumbler allows the use of multiple media
2.6 The Intrusive Internet
Malware refers to software programs designed to damage or do other unwanted actions on a computer system.
1. Spamming 2. Spoofing 3. Phishing 4. Pharming 5. Cookies 6. Spyware
Snooping Email is not private
1. Corporate management has the right to view employees’ email 2. Friends can send email anywhere 3. Not all ISPs protect their customers’ privacy
Spam: Electronic Junk Mail
1. Unsolicited email that takes up your time 2. Delete it without opening the message 3. Never reply to a spam message 4. When you sign up for something, don’t give your email address 5. Use spam filters 6. Fight back by reporting new spammers to www.abuse.net or www.spamhaus.org
Spoofing
1. Using fake email sender names so the message appears to be from a different source, so you will trust it. 2. If you don’t know the sender, don’t open it.
Phishing
1. Sending forged email directing recipient to fake website 2. Purpose: to entice people to share personal or financial data 3. Fake website looks like real website, such as a bank’s
Pharming
1. Thieves implant malicious software (malware) on your PC 2. Redirects you to an imposter web page even when you type the correct URL 3. Use websites with URLs that begin with “https://: 4. Some spyware removal programs can correct the corruption
Cookies
1. Little text files left on your hard disk by some websites you visit 2. Can include your log-in name, password, and browser preferences 3. Can make visiting these websites next time more convenient and faster 4. But cookies can be used to gather information about you and your browsing habits; this information can be used without your consent
Spyware
1. Software surreptitiously installed on your computer via the web 2. Spyware hides on your PC and captures information about what is on the PC, such as keystrokes, passwords