Google’s web semantics & techniques
By far, Google owns the biggest database on the web today, with over 1.5 billion pages.
Google presents relevant results by using mathematical formulas to rank web pages based on the significance & importance of the pages that link to it.
 The philosophy is that high-quality websites point to other high-quality websites.
  Basically when a search is being made, Google determines web pages that meet the search criteria and then lists the most popular sites among high-quality resources at the top of the list.
Google does not seem to support full Boolean AND NOT. However, it does allow the implied Boolean minus sign (-). When multiple keywords are entered, all keywords are treated as “AND” queries. Because Google automatically returns pages that include all keywords, the plus sign (+) and the operator AND are not necessary. Also, quotation marks for phrase searching are not required as Google returns pages with keywords in close proximity.
So far, throughout its Advanced Search Page, Google supports link searching and title, domain and host searching. Using the Image, News Articles, Discussion Groups Databases, and users can search for a whole range of diverse things.
Unlike other search engines, Google offers a cached copy of each result, which can be extremely helpful if the site’s currently not available.
Beware other search engines! Google’s is going to stick around for a long time. Better fasten your seatbelts, or just start creating a professional unique development plan to dethrone Google of its highest peaks!
