WWW Concepts

Introductory Concepts

• The Internet is a global network of connected computer systems that allows people to communicate electronically
• The World Wide Web is a hypermedia-based system for graphically displaying information
• A Web browser is a program which allows you to navigate the web, such as Netscape Navigator or Internet Explorer or Opera
• All computers and software which make up the Internet are either clients (which request and receive data) or servers (which provide data).

Some common abbreviations and terminology

Using a Web Browser

Your starting home page

This is the default page on the WWW that your browser displays at startup. You return to it at any time by clicking the home button in the button bar (the one with the little house on it). You can decide what page is displayed here by editing your preferences. Some browsers call this the Start Page to distinguish it from your Personal Home Page (which would be a page about yourself that you published on the web). The term Home Page means the entrance page to a Site, a collection of webpages in the same location.

Changing pages

What is a URL?

URL means Uniform Resource Locator, indicating that this is a form of addressing any kind of resource on the internet in a way understood by all kinds of different computers and operating systems.

• Parts of a URL: protocol:(//)subdomain.domain.suffix
  • protocol
    • http:// (for hypertext, the main web-format)
    • ftp:// (for file transfers, one at a time)
    • mailto: (for sending email)
    • file:// (for opening a local file on your computer)
    • wais, gopher etc. are hardly useful anymore
  • suffix
    • .com (commercial)
    • .gov (government site)
    • .mil (military)
    • .edu (educational)
    • .net (network)
    • .org (non-profit organization)
    • .us (United States)
    • .uk (United Kingdom)
    • .jp (Japan)
    • etc. (two-letter abbreviations to indicate the country)
  • domain
    • uic.edu
    • netscape.com
    • arthritis.org
  • subdomain
    • www.uic.edu (on tigger)
  • www2.uic.edu (on icarus)

The easiest way of changing pages is clicking hyperlinks on existing pages

• A hyperlink is an item (text or picture) that allows you to access another page on the Web or even another section on the same page
• In text, hyperlinks are usually indicated by being underlined
• When pointing at a hyperlink, the mouse turns into a pointing hand
• The status bar at the bottom of the window shows the URL you would jump to when the pointer hovers over a hyperlink
• In newer browsers, a little white bar with the URL pops up when the pointer hovers over a hyperlink

Loading pages

• Since pages can be very large in some cases, they take time to download, especially over modem lines
• Pages with many graphics take the most time to load
• Complex tables cost your computer a lot of effort, so even when they are downloaded quickly, they may take a long time to display
• Stop a long download by clicking Stop button (often a "stuck" download works fine if you try it over!)
• Downloading graphics can be turned off by going to Edit->Preferences Menu, going to the Advanced section, and turning off (=uncheck) "Auto Load Images"
  • Images then are replaced by a small icon
  • To see a single image, click on its image icon
  • To see all images on a page, click on the Image button on the toolbar (this button is only shown when you have "Auto Load Images" turned off)

Navigating pages

• Use back button in main toolbar
• Right-click anywhere in browser window (for Windows users) and select back
• Use Go-Menu to go back several pages at once
• On newer browsers, the back button (or a little arrow beside it) functions as drop-down list of the last few pages visited
• The History, a list of all pages seen "recently", is available from the Communicator drop-down menu. It keeps track for various days (configurable) of all places you visit.
• Click on the drop-down arrow to the right of the current URL location for a list of some URLs you recently typed in

Cache of pages

• Netscape keeps a certain percentage of pages you've been to loaded into memory, so you may return to them quickly
• On the toolbar, use the Back and Forward buttons to see these pages
• Go directly to a cached site with the
  • List under the Go menu
  • History option
• Reload button on toolbar will reload the current page
  • There may be a need to get the most updated information on a specific page
  • Example: reloading the traffic congestion map on the UIC home page.
    Auction sites, on the other hand, usually refresh automatically every so often (that's part of the page's code)
  • Images generally don't get re-loaded, to see updated images, clear the cache first

To adjust cache settings, go to Edit-> Prefences-> Advanced-> Cache menu and change size or location of cache file or empty the cache file.

Opening several browsers

• Some links will open up a second browser window to display a remote site without leaving the referring site
• Users can go to File menu to open another browser window
  • while you wait for something else to download
  • to compare or contrast information
  • if your current site contains forms and you don't want to lose information while checking on a link

In Edit-> Preferences you can set the number of browser windows that can be open at the same time.

Bookmarks

• Allow you to save specific URLs so they can be visited again
• Saved on your private machine only, not accessible elsewhere!
• For details, see our bookmarks page

Scrolling

• Longer pages require scroll bar down the right side of window
• If necessary, there is a horizontal scroll bar at the bottom of the screen (shows bad page design!) due to large images or too wide tables
• Often, you find scroll bars in pages with frames. These can be turned off by the page designer, so that part of the frame is invisible to you (shows bad page design!)
• For long pages, a scrolling mouse (or software imitating it) is extremely useful, in particular the "panning" feature, which allows moving around in the page without holding down any mouse buttons, and thus avoids repetitive strain injury.