Search engines work a lot like old-fashioned library card
catalog systems when it comes to scanning the estimated 50
billion-plus pages that comprise the Internet. Say you’re
searching for a book on how to write a business plan at your
local library — maybe in the days before card catalogs were
computerized. First, you’d look in the “B” drawer of the catalog
system, flipping through index cards until “business plans”
appeared in a card’s subject line. Then you’d jot down the shelf
location of the book you wanted and search the stacks until you
found your selection. Internet search engines are based on a
similar concept. Type “business plans” into a search engine and
it will scan Web pages for matches, and then list them according
to relevancy. This is because popular search engines such as
Google, Yahoo, and MSN don’t search the World Wide Web directly.
Instead, they scan proprietary databases that rank Web pages
according to specific criteria established by each search engine
company. The challenge for busin