Intro

It is amazing that the Google search engine has only been around since 1998, though Sergey Brin and Larry Page actually began development of the technology in 1995. See the Google History (http://www.google.com/corporate/history.html) Web page for a full discussion of the evolution of the technology and the company

Pagerank ranking technology

What was particularly important about the search engine technology (though Google may be moving from it) was the way of ranking results of a search. Specifically, Brin and Page developed a "link analysis" algorithm ("pagerank") which ranked the pages resulting from a search according to what other and how many Web pages and sites linked to a particular Web page. Part of the ranking involved an assessment of the repute of the other Web sites/pages and assumes that more respected Web pages will link to other quality Web pages.

Example: You do a search on "medical ethics." Pageranking brings up the following Web sites in the first five results:

• BioMed Central | BMC Medical Ethics
• Journal of Medical Ethics
• MedicalEthics.ca -- The Canadian Resource for Medical Ethics
• Bulletin of Medical Ethics - Homepage
• AMA (Ethics) Principles of Medical Ethics, June 2001

Combined with conventional ranking

• Part of Google's ranking also involves traditional statistical ranking in which the number and location of occurrences of the search terms that you entered is evaluated.
• Factors that are evaluated include:
  • The frequency of occurrence of the entered terms on Web pages. The higher the number the higher in the returned records candidate Web pages are ranked.
  • The location of the search terms in the Web pages. Higher ranked pages include ones where the search terms occur in the title and towards the top of the text in the Web pages.

Major components include:

• Web search
  • The search engine offers both Basic and Advanced search capabilities.
  • See the pages on the individual search modes.
• Newsgroup search ("Groups")
  • Hundreds of millions of messages from the UseNet archive of newsgroups or discussion forums are in this database. Sometimes such messages can be very good sources of information, but you have to carefully evaluate their content because they are mostly personal messages from discussion groups.
  • These messages date back to the early 1980s because the Google "groups" database is actually composed of the old DejaNews database of newsgroup messages plus all the newsgroup content gatherd by Google since the acquisition of DejaNews.
  • The Advanced Image search offers Boolean and phrase-searching capabilities by specialized entry fields.
  • Limits:
    • Newsgroup - Enter newsgroup by name.
    • Subject - Words that you expect to find in the subject line of a newsgroup message.
    • Author - You can enter the name of a person that you expect to find in the "From" field of a newsgroup message.
    • Message ID - This is the complete URL for a specific message.
    • Language - You can limit returned records to any of dozens of languages. The default is "any language."
    • Date - You have a choice of a:
      • Pulldown menu - Choose anytime, last hour, last day, past week, or past month.
      • Date range - You can enter a range of dates in the last two months.
  • Resource: Google Groups Help - http://groups.google.com/googlegroups/help.html
• Image search
  • At about 900 million images, this image database is the largest one available online.
  • The Advanced Image search offers Boolean and phrase-searching capabilities by specialized entry fields.
  • Limits:
    • Image size - Select small, medium, or large.
    • Image file format - Select .jpg, .gif, or .png.
• News search
  • For up-to-the minute (well, maybe 15 minutes) news, this is one of the best tools available online.
  • The News search accesses and indexes about 4500 different online news sources.
  • More important news sources (such as the news network sites and the news syndicates) are downloaded as often as every 15 minutes.
  • The Advanced News search offers Boolean and phrase-searching capabilities by specialized entry fields.
  • Limits:
    • News source - Enter a news service, periodical, web site.
    • Location - You can limit the returned records from news sources in a specific state or a country.
    • Occurrence - Where in the record do the terms occur? Enter anywhere, in the headline, in the body, or in the URL.
    • Date - You have a choice of a:
      • Pulldown menu - Choose anytime, last hour, last day, past week, or past month.
      • Date range - You can enter a range of dates in the last two months.

Other Tools & Information

• Froogle search
  • x
• Google Alerts
  • x
• Google Labs
  • x
• Google
  • x