The World Wide Web

1
The World Wide Web

• A part of the Internet.
• Developed by a research institute called CERN to
  share pictures and data.
  
• Early browsers include Mosaic.
• Allowed to grow when the backbones (high
  bandwidth connections) were allowed to become
  commercial in the early 90s.

2
Web Browsers

• Clients connect to servers.
• They download data and interpret it.
• The data is in (HTML) source code and binary
  form.
  
• Most are highly configurable.
• Can store preferences.
• Can store favorite sites.

3
Examples of Browsers

• Text browser Lynx
• Graphical Browsers
• Internet Explorer
• Netscape Navigator
• Mozilla
• Opera
• Wireless/PDA browsers.

4
Browsing

• You can download and possibly upload
• Webpages
• Data files
• Computer Programs
• Music/Sounds
• Pictures/Movies
• (But dont steal! People work very hard to make
  the things you enjoy!)

5
Browsing 2

• Browsers connect to servers using TCP/IP
• Like when I connected to www.umd.edu port 80
  using telnet.
  
• They can be used as
• Email clients
• Newsreaders
• Simple webpage makers
• File viewers

6
Redundant Slide

• To get this slide, start a browser.
• Go to http//www.cs.umd.edu
• Click on Class Web Pages.
• Click on CMSC102 link at top of page.
• Click on Part6.
• View the slide in MS Word or Powerpoint.
• Then you dont need to view this slide.

7
Netiquette

• Dont post or send inflammatory messages.
• Everything is (or can be) recorded.
• Assume that whatever you type will be around
  forever.
  
• People use the Net to check up on prospective
  hires.
  
• So what you type now may haunt you forever.

8
Netiquette 2

• Flaming writing rude, obnoxious messages
  should be avoided.
  
• Spamming should be avoided.
• Sending useless annoying messages to boards or
  newsgroups.
  
• sending many pieces unsolicited email.
• Avoid off-topic or inappropriate messages.
• Things ok in alt.sex.bears but not elsewhere.

9
Lynx A Text Browser

• Type lynx within a Unix account to use it.
• Move around with arrows.
• Left/Right are backward/forward keys.
• Up/Down move around links in current page.
• Go lets you open a new address
• Can toggle buttons and enter text.
• Can set options/preferences.

10
Netscape Browser Menu

• File -- open new pages/windows, edit page.
• Edit -- Search, edit preference, find in page
• View -- See page source, change fonts.
• Go -- forward/backward/home
• Communicator -- mail, news, AIM, addressbook,
  bookmarks.

11
HTML

• HTML -- Hypertext Markup Language
• Lets you send text.
• Contains formatting information.
• Can contain pictures, sounds, other things.
• Extends presentation beyond text.
• Lets you access other information by linking
  to other documents.

12
Hypertext

• HTML is not the only markup language.
• TeX/LaTeX for mathematical typesetting.
• Example
• Name John Arras
• Credits 68
• GPA 2.56
• Housing Off-Campus
• Select name to get John Arras, etc

13
URLs

• Uniform Resource locators.
• Ex http//www.umd.edu/classes/index.html
• Resource type http.
• Others telnet, ftp, mailto, gopher, nntp
• Host www.umd.edu
• Directory and file classes/index.html.

14
Start using Netscape

• Some search engines
• www.lycos.com
• www.yahoo.com
• www.google.com
• www.overture.com
• www.askjeeves.com
• Your ISPs homepage.

15
Customization

• Boomarks -- good sites to remember.
• List them
• Edit them
• Preferences -- change settings
• Fonts
• Mail/newsgroup settings
• Cache/cookies

16
Interesting sites

• www.umd.edu
• www.theonion.com
• www.washingtonpost.com
• www.nasa.gov
• www.fark.com
• www.slate.com
• www.salon.com

17
Some File Types

• .txt -- Plain text file
• .html -- html file
• .mp3 -- mpeg3 sound (music file)
• .wav -- WAVE sound file
• .zip -- PKZIP compressed file
• .mpg -- MPEG compressed movie
• .gif -- Graphics Image Format
• .jpg -- JPEG compressed picture

18
Other features

• Plugins or viewers to listen/view different file
  types.
  
• CGI (Common Gateway Interface) Lets Web servers
  run programs.
  
• Servers may run Java or other scripts or special
  HTML codes.
  
• Dynamically generated webpages.

19
Usability Issues

• http//www.otal.umd.edu/UUGuide/
• Blind -- Text vs. graphics.
• Lawsuits vs. major companies over this.
• Cognitively disabled --Alzheimers.
• Novice vs. Expert -- Learning Curve.
• Low Income -- Access to technology.

20
Usability Enhancements

• Adaptive software, adjusts to the user.
• Multiple Bandwidth options.
• Online help.
• Media conversion -- video to audio.