Mosaic was created during a four-month period in late 1992 and early
1993 by Marc Andreessen and some other students
NCSA's Software Design Group -- produced versatile, multi-platform interface to World-Wide Web -- called it Mosaic
Mosaic was created during a four-month period in late 1992 and early
1993 by Marc Andreessen and some other students
Due to easy, point-and-click hypermedia interface, Mosaic set standard for Web interfaces
Marc Andreessen left University of Illinois to become Vice President for Technology of Netscape Communications
First version of Netscape browser available October, 1994
Big improvement -- Continuous document streaming, enabling users to view documents while they were still being downloaded rather than waiting for the entire document to load
Netscape has been responsible for advances in HTML
Microsoft's Internet Explorer also based on Mosaic browser
Developed specifically for use with Windows 95 operating system
Now about equally popular. Each has proponents with almost religious zeal.
More Web pages are now retrieved by Internet Explorer clients than Netscape clients
Lack of compatibility of some features makes advanced Web design challenging. Pages should work well on both browsers (as well as recent versions of both).
Buttons: Back, Forward, Reload, Home, Search, Print, Stop
Location field displays URL of document being viewed
Viewing area displays contents of current document. Highlighted or underlined words or images within viewing area are hyperlinks to other document. Use scroll bar on right side of viewing area to move through document contents.
Some hyperlinks open in separate windows. These depend on external viewers. Generally true for some graphics, sound, and video.
Web browser displays information such as status of retrieval of file, use of external viewer, URL of linked file, ....
BACK -- Return to previous Web page. Repeated clicks of Back button continue back to previously viewed pages.
FORWARD -- Proceed to next Web page. Can only be used if Back button has been used to go backwards. Then, Forward button can be used to go in other direction.
RELOAD -- Reload current Web page from its server if it has changed from version you are viewing. Browser sends time-date stamp to server. (This button is called "Refresh" by Microsoft Internet Explorer).
HOME -- Proceed to "home page" for your Web browser -- page that appears when Web browser application begins running.
SEARCH -- Bring on-screen a page that can be used to search Web for some information. Provides access to some of standard Web Search Engines.
PRINT -- Print Web page currently being viewed. Prints entire Web page you are visiting -- not just portion shown on screen.
STOP -- Discontinue attempt to load this Web page. Useful for lengthy Web page with lots of images arriving slowly.
Open Page -- Brings up little box on screen into which you can type URL of Website you would like to visit. Same effect can be achieved by typing in URL at location field. Another thing that can be done with "Open Page" selection is to click on "Choose File" button. View files stored on your own computer disk. Can be useful when creating Web pages so that you may preview them before moving them to Web server.
Print Preview -- Before printing Web page, get an idea how information is going to print -- specifically how many pieces of paper will be printed and what will be on each one.
Print... -- Same as Print button.
Close -- Closes current Netscape Navigator window, but leaves open any others you may have Opened. If you have only one Netscape window open, effect of Close entry is same as Exit.
Exit -- Close all open Netscape Navigator windows and shut down application.
Copy -- Hold left mouse button down and drag cursor across some text. Text is highlighted by putting it into reverse video. Clicking Copy entry puts this text into text "buffer" so that it may be used later.
Paste -- Equivalent to typing text in text "buffer" into application at point where cursor is currently located.
Cut -- Both copies and removes text from an application. Cannot be used with Web pages.
Find in Page... -- Brings up little box. Type in character(s), word, or phrase that you want to find in current Web page. Can search multiple times for same phrase, match case exactly, and search both forward and backward in document.
Preferences -- Brings up window with lot of choices that you can make to set up Web browser to work exactly way you want. Some major Preferences include:
Appearance -- On this page you can choose whether you want buttons to be "Pictures and Text", "Pictures Only", or "Text Only".
Fonts -- Choose style and size of font to be used for both Variable Width (normal) text and Fixed Width (special typewriter-like) text.
Colors -- Choose colors to be used for text (default is black), background (default is white), unvisited links (Web pages you have not visited recently -- default is blue), and visited links (Web pages you have visited recently -- default is purple).
Navigator -- Specify "home page" you want displayed whenever Netscape Navigator is started or whenever you click "Home" button. Also, specify how many days must pass since you last visited Web page before it is to be considered unvisited.
Mail & Newsgroups -- There are several screens of information that must be provided if you want to use Netscape to send and/or retrieve email for you. Major items involve specifying your name, return email address, and outgoing and incoming mail server information.
Advanced -- Specify whether you want images loaded automatically (default as opposed to asking for images to be loaded later when you find an interesting Web page) and whether you want to accept or reject cookies.
Cache -- Specify size of your memory
and disk cache. (Probably best not to change from default
sizes unless you really know what you are doing.) Also specify
how often you want to check with server to see whether newer
version of Web page is available and should be sent by server:
"Once per session" is default and checks Web pages first time
each is accessed after starting up browser.
"Every time" asks appropriate server to check time and date of current
Web page every time you access page.
"Never" instructs your Web browser always to use cached copy if
available and only to go to appropriate server if particular Web page
is no longer available in either memory or disk cache.
Show -- Location Toolbar contains location field and button to get to your Bookmarks. Hide this or get it back on-screen by choosing entry "Location Toolbar".
Increase Font -- Increase both Variable Width and Fixed Width font sizes to next larger size -- slightly faster than going through Edit pull-down menu's Fonts screen.
Decrease Font -- Decrease both Variable Width and Fixed Width font sizes to next smaller size -- slightly faster than going through Edit pull-down menu's Fonts screen.
Reload -- Same as Reload button.
Show Images -- If Edit pull-down menu's Advanced screen has been set so that images are NOT loaded automatically, choosing this entry requests all images for current page from appropriate server.
Refresh -- Re-paint screen with information for that page currently in memory.
Stop Page Loading -- same as Stop button.
Stop Animations -- Some images are really collections of separate
images that are repeated by Web browser to give appearance of
animation. Sometimes, they can become distracting. Stop Animations
temporarily freezes all animated images on current Web page.
Page Source -- Brings up new window containing the HyperText Markup Language (HTML) file that comprises this Web page. This can be useful when creating Web pages so that you may observe specifics of how other people display information.
Page Information -- Brings up new window containing information about size of Web page, last modification date, location of images it uses, etc.
Forward -- Same as Forward button.
Home -- Same as Home button.
Remainder of Go menu is numbered list of most recent pages (in order) that you have visited. Current Web page is numbered "0", one before that "1", one before that "2", etc. By simply clicking on one of these pages you can leap back to a previously-viewed Web page much more quickly than by repeated clicks of the Back button. Can also click on page "0" to return to where you were much more quickly than by repeated clicks of Forward button.
At bottom of this menu will be entries for each Netscape window that is open ... allowing easy movement back-and-forth among them as well.
Add such Web page to your Bookmarks. When you are visiting interesting Web page, click on Bookmarks icon on Location Toolbar and select "Add Bookmark". Later, any time you click on Bookmarks icon on Location Toolbar, interesting Web page will be among those listed. Simply click on that entry and off you go to interesting Web page.
Usually best to add home page of Website to your Bookmarks rather than just some page you find at Website. Websites are frequently re-organized with Web pages being moved and even re-named. Bookmark to subpage may not work after a while, but it is highly unlikely that bookmark to Website home page will become defunct any time soon.
Occasionally you decide that bookmark that was very useful for a while is no longer of much interest to you. Click on Bookmarks icon on Location Toolbar and choose entry "Edit Bookmarks". In little window that appears, click on particular bookmark and then select Delete from Edit pull-down menu. Particular bookmark is now deleted from your list.
"Cookie" is little morsel of information sent from Web
server to Web browser (usually during first visit)
After browser receives cookie, whenever requests Web page from that server, sends back that cookie
Shopping applications can store information about past (or currently) selected items
Fee services can send back registration information -- freeing client from typing IDs and passwords
Sites can store user preferences on client
Cookie might be...
.msn.com,Science&Technology,
Dilbert,Local Weather
Why keep cookie at browser instead of server? Faster!
Cookies can be modified, removed, expired
Cookie limit -- cookies used least recently removed
Robots, Crawlers, Worms, and Spiders
"Crawl around and find what we can"
Continuously running program (robot, crawler, worm, spider) pursuing hyperlinks throughout Web
Start with set of documents. Identify new places to explore by looking at outbound links. Visit those links. Index most useful terms.
Lycos project at Carnegie-Mellon
"Lycos" name comes from arachnid family Lycosidae
Started by Dr. Michael Mauldin, Carnegie-Mellon University in 1994
Yahoo was created by Stanford graduate students Jerry Yang and David Filo in 1994
Name "Yahoo" is either corruption of "YangFilo" or "Yet Another Hierarchical Officious Oracle"
MetaCrawler calls several other search engines and reports their collective results
Problems with Search Engines --
Effective descriptive phrases
Search Engines show Web as it was, not as it is
Links that don't work or have been moved
Reluctance to take corrections from Website creators
Solution??? --
Required registration ... rather like requiring card in card catalog
.wav, .aif, .aiff, .au, .mpeg, .mp3, .mid, .mov, .avi
File had to be downloaded to browser in its entirety before playing began
Such files could be very large. Delay could be lengthy.
Streaming audio/video begins playing almost immediately and can continue indefinitely
Can be used for "live" events
Streaming audio/video player required. Can be launched by browser or embedded in browser window.
RealAudio, LiquidAudio, Streamworks, Shockwave Audio, RealVideo
Java applets
Background sounds
Macromedia Flash images and video
Adobe Portable Document Format (PDF) -- requires Adobe Acrobat software
Links to subpages
Be consistent among pages at Website
General rule -- don't make long pages
Each page has link (buttons or images are nice) back to homepage
Each page has reference to person responsible
Each page has "last changed" date
Judicious use of background images and text colors
Judicious use of images
Design for multiple browsers
"Stealing" techniques from other people
Can link to any Website, but do not steal material
Reference things taken in part from other sites and give URL
Avoid items in poor taste -- that you would not show to your mother
