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Introduction to Computer Science

Introduction to Computer Science

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Introduction to Computer Science

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  1. Introduction toComputer Science The Internet and World Wide Web

  2. What is the Internet? • The Internet is a large connection of networks. • The Internet is not controlled by any agency. • It contains a variety of services, one of which is the World Wide Web. When I took office, only high energy physicists had ever heard of what is called the World Wide Web…Now even my cat has its own page. Bill Clinton, 1996 The Internet and World Wide Web

  3. ARPANET • The Internet started as ARPANET in 1969 • US Dept. of Defense • Allow scientists to share information • Continue to function if parts were destroyed • Originally just four main computers housed in four different universities The Internet and World Wide Web

  4. NSFnet • National Science Foundation attached its network (NSFnet) to the ARPANET in 1986. • Became known as the Internet • In 1995, the NSF removed itself as the primary manager of the Internet. The Internet and World Wide Web

  5. The Internet Backbone • The Internet backbone handles the bulk of Internet traffic. • The points of connection are National Access Points (NAPs), also called point of presence (POP). • An ISP/OSP that has a direct connection to a NAP is referred to as first-tier. Read moreabout theInternetinfrastructure at The Internet and World Wide Web

  6. Connecting to the Internet • "Dial" into an ISP or OSP using a phone modem, DSL, cable modem, etc. • ISPs and OSP have permanent connections to the Internet. • The ISP/OSP provides temporary access to the Internet through their connection • Once connected, you request web pages and other services, likee-mail and news groups. The Internet and World Wide Web

  7. America Online • America Online is a very popular online service provider. • In addition to Internet access, AOL users get easy-to-use news and entertainment. • AOL provides a portal service to users, making access to different types of information easier. The Internet and World Wide Web

  8. Broadband: DSL and Cable • Broadband connections allow more data to travel between your computer and the Internet. • DSL and Cable are the two most common broadband choices for home users. Both cost approximately $40-$50 per month. • DSL (and ISDN) relies on the telephone cables managed by your local phone company. • Cable relies on the Coaxial cables managed by your television cable company. “The number of broadband users in the US nearly tripled in the past two and a half years to more than 48 million subscribers, according to a report by the US Federal Communications Commission (FCC).” September 2004 The Internet and World Wide Web

  9. Dial-up Internet Access • “As prices dropped over the past year, broadband use at home has surpassed that of dial-up in the United States, reaching 53% of residential Web users in October, according to Nielsen/NetRatings. ” • • December 2004 • Dial-up Internet access is still quite popular. Although it is a slower type of connection, it has some benefits: • Affordable • Uses standard phone lines • Adequate for most web surfing and e-mail The Internet and World Wide Web

  10. Connection Speed Trends The Internet and World Wide Web

  11. Bright Idea • Visit and research cable internet access. • What type of internet access is the major competitor to cable? • Visit to find out how cable modems work. • What type of cable is used for cable internet? • Why do connections speeds vary with a cable modem? The Internet and World Wide Web

  12. World Wide Web • The Web is a service on the Internet. • The Web is a collection of web documents on the Internet. • Each web document has an address, called a URL, or Uniform Resource Locator. • We use web browsers to display web pages, just as we use Word to display Word documents. The Internet and World Wide Web

  13. The W3C • The World Wide Web Consortium • Non-profit organization based out of MIT (Mass. Institute of Technology) • W3C members include hundreds of software and hardware companies • Directed by Tim Berners-Lee, founder of the WWW • Sets standards for many areas of the Internet The Internet and World Wide Web

  14. Web Browsers • Web browsers are applications that read web pages (HTML files). • Microsoft's Internet Explorer is the most common browser. • Others include Netscape Navigator, AOL, Opera, and Mozilla. • New browsers have better support for Web standards and greater security. • You should upgrade to a recent browser when possible. The Internet and World Wide Web

  15. Microbrowsers • Handheld browsers have limited graphics capabilities • Some Web sites have alternate version sites for users with such devices • Obviously, web designers need to take into consideration the small screen size of handheld browsers when adding content and features to a site. The Internet and World Wide Web

  16. Finding Web Pages • Enter the domain name for a web site in the browser's address bar. • The browser finds the server and requests the default page (usually index.html). • home.html is another default. • The server honors the request and the browser downloads the web page from the server to your computer. • This whole process can take place in just a few seconds. The Internet and World Wide Web

  17. Anatomy of a URL The Internet and World Wide Web

  18. Downloading • When you view a Web page, you are viewing a copy of that page that has been downloaded to your computer. • You are not looking at the actual page on a Web server. • Pages that are large or contain a lot of graphics, download slower and will take longer to display. • Web designers need to find the balance between an attractive site and one that downloads quickly. The Internet and World Wide Web

  19. Bright Idea • Visit and research top-level domain names. • What was the intended purpose of .net and .com? • Visit and do some research. • What is cybersquatting? • How much was spent for domain names like and The Internet and World Wide Web

  20. Web Pages • Most Web pages are written in a language called HTML—Hypertext Markup Language. • Your web browser reads HTML and ‘translates’ it into a user-friendly web page with pictures and colored text. • HTML, it its basic form, controls the markup (look) of text. • Bold, italics, size, color, etc are all controlled by HTML • This word is <b>bold</b>, and this word is <i>italicized</i>. The Internet and World Wide Web

  21. HTML is Plain Text • HTML is a plain text language that can be written using any plain text editor. • Notepad is sufficient for writing even the most complex web pages. • Although programs like MS Word can save files as .html, this does not make them an ideal HTML editor. • There are hundreds of free and cheap HTML editors with various features available for download. • There are also popular programs such as FrontPage and Dreamweaver that create web pages. The Internet and World Wide Web

  22. Basic Web Page Marks the beginning of the HTML document Marks the beginning of the body of the page. The part that people see in their browsers Header information for the Web page. Used by search engines Tells the browser which version of markup language is being used The Internet and World Wide Web

  23. Cascading Stylesheets • Cascading Style Sheets control the formatting of HTML elements • HTML sets the structure of the document, while CSS gives the page color and other characteristics • One css file can be used to format thousands of web pages so that they all have a similar look. The Internet and World Wide Web

  24. Uplodaing (Publishing) • After the page is made, upload the page to a Web server • Your ISP may provide server space for you • Your UCF fees include space on the UCF Web server • When you store a page/site on someone else's server, you have to follow their rules The Internet and World Wide Web

  25. File Transfer Protocol • FTP is the protocol used to upload and download files between a local computer and a server • You will use FTP to send your Web pages to the UCF server • You can FTP within the browser, or • You can download and install an independent FTP program. I use WS_FTP. The Internet and World Wide Web

  26. Promoting Your Site • Promoting your site will get more users there. This will increase traffic, and perhaps revenue • Give your URL to friends/family • Include your URL in your e-mail signature • Post your URL in discussion boards and newsgroups • Submit your URL to a search engine or web directory The Internet and World Wide Web

  27. Search Engines • Search Engines continually build a database of Web pages by collecting titles, descriptions, and page text. • They use programs called spiders or robots to search the Web and collect data. The Internet and World Wide Web

  28. A Good Search Engine • Two key factors make a search engine a good search engine. • The size of its database • The larger the database, the more likely your search results will contain the most recent information • The ranking of results based on searches • Relevant sites to the user’s search words must be located at the top of the listings. Otherwise, user’s will try a different search engine. The Internet and World Wide Web

  29. Using Search Engines • Learn basic search techniques to improve search results • Use quotation marks for exact phrases. • Use + and – signs to include or exclude words. • Use “and” and “or” operators to widen or narrow the search. The Internet and World Wide Web

  30. Web Directories • Web directories are lists of web sites organized by topic. • A hierarchical structure is used to make finding sits for a particular topic easy. • Sites in web directories are added by people, so the site is really about the topic the user is interested in. • As the programming behind search engines improves, the emphasis on web directories declines. The Internet and World Wide Web

  31. Portal Sites • Provide a variety of services and links on one page • Want you to make them your home page • The page that displays when you start your browser The Internet and World Wide Web

  32. Web Communities • Families of related (sometimes loosely) Web sites • WebReview provides articles and forums for web designers. • iVillage provides info on a wide range of topics geared towards women. • Yahoo Groups maintains web communities for all types of groups. The Internet and World Wide Web

  33. Online Communications • E-mail • The recipient's e-mail address is entered into the TO: field • The message is delivered to the appropriate mailbox and stored • The recipient logs into their mail server and uses Post Office Protocol (POP) to download the message to their local computer • Newsgroups • A newsgroup is a collection of threaded discussions about a particular topic • Chatting • Allows multiple users to communicate in real-time The Internet and World Wide Web

  34. Netiquette • Netiquette is the code of acceptable behavior while on the Internet. • Keep messages brief • Use clear subjects • Don’t use all caps • Avoid sarcasm • Don’t write e-mails when upset • Include your name The Internet and World Wide Web

  35. Multimedia • Combination of elements • text • graphics • sound • video • Multimedia can add richness to a Web site, but may greatly increase the download time. The Internet and World Wide Web

  36. Web Image Formats The Internet and World Wide Web

  37. Bright Idea • Visit and research handheld devices for communication. • What is a blackberry? • What is wi-fi? • What is bluetooth? • Visit to find out about mobile browsing. • What is the benefit of an xhtml browser? • Are choices extremely limited for xhtml-capable phones? The Internet and World Wide Web

  38. Animated GIF Images • An animated gif is a series of still GIF images shown in rapid succession to create an animation. • Movies are like this. A movie is a series of still photographs shown one-by-one so that we see movement. • Animated GIFs are fine for simple animations, but they can quickly become large (file size) and slow down the download process. • Flash animations can make cool animations with a relatively small file size. The Internet and World Wide Web

  39. Thumbnail Images • Small versions of a large image • Very useful on the Web • Improves download time for the Web page • Let Web users know what the image is before they decide to wait for a possibly long download. The Internet and World Wide Web

  40. Raster (Bitmap) Images • Lite-Brite displayed images made up of individual pegs of color. • Bitmap images (raster graphics) work the same way. • However, a computer generated bitmap can produce millions of different colors and the points of light are very small. The Internet and World Wide Web

  41. Creating Bitmaps • We don’t use Lite-Brites, to make bitmap images, instead, we use computer hardware and software. • Adobe Photoshop • Jasc Paint Shop Pro • Microsoft Paint • Digital Cameras • Scanners The Internet and World Wide Web

  42. Vector Images • Like all vector images, the one above is made up of many polygon shapes. These shapes overlap each other in layers and together create the boat. • Vector graphics do not use a bit map structure. Instead, they use instructions that describe the size, shape, and color of the parts of the image. • This allows vector images to be resized quite easily without affecting quality and without affecting filesize. The Internet and World Wide Web

  43. Audio on the Web • Waveform is the digital reproduction of a natural sound. • Natural sounds are analog—they are varying strengths of a wave. • A digital sound uses sampling to produce a sound similar to the natural sound. The Internet and World Wide Web

  44. Audio Formats • Popular formats include • WAV • MP3 • WMA (Windows Media) • RM (Real Media) • Some formats can be played from the browser, others require a plug-in (supplemental application) The Internet and World Wide Web

  45. Bright Idea • Visit and research how mp3 files work. • How does the mp3 format make audio files smaller? • What is perceptual noise shaping? • Visit to research the AAC format. • What are some advantages of AAC over MP3? The Internet and World Wide Web

  46. Common Plug-ins • Plug-ins are often used when browsing the web. Some well know apps include • Acrobat Reader (Adobe) • Flash Player and Shockwave (Macromedia) • QuickTime (Apple) • Real Player (Real) • Windows Media Player (Microsoft) The Internet and World Wide Web

  47. Streaming Media • Some audio and video can be played while it is downloading • Allows users to start enjoying the media without a long wait • Slow Internet connections can cause the media to stop playing intermittently while more of the file is downloaded The Internet and World Wide Web

  48. Video on the Web • Video for the Web must be reduced in size and quality for fast downloads. • Most web video will have a grainy look and display in a small size. • Video can be embedded into a web page. • The user will need a player (plug-in) to watch the video. The Internet and World Wide Web

  49. E-commerce • B2B (Business to Business) or B2G • The book publisher sells the text books to the UCF bookstore • B2C (Business to Consumer) • The UCF bookstore sells the books to students • C2C (Consumer to Consumer) • Students sell the books to other students The Internet and World Wide Web

  50. Shopping Carts • Technology that keeps track of a customers items prior to purchase. • Cookies are often used for this • Shopping carts allow us to shop around different parts of the online store before starting the check-out process. • Some online stores can even ‘remember’ what we put in our shopping carts the previous week or month. The Internet and World Wide Web