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How search engines work
A Few of the Methods Search engines
use to Rank their listings:
1. Expert Guide
Sites
- These sites help users find answers
to any question by using either paid or volunteer guides
in real time.
- An example of an engine that does this
is About.com
2. Pay-Per-Click Search Engines
- Rank sites by allowing web pages to purchase
their ranking under any keyword combination
- An example of an engine that does this
is GoTo.com
3. Popularity engines
- Rank sites according to the number of
users that have clicked on a particular site for a given
word
- An example of an engine that does this
is Google
4. Meta Search Engines
- Rank sites using tools which check
numerous search engines and then return a listing of matching
web pages based on the pages that scored highest on the
keyword relevance
- An example of an engine that does
this is Metacrawler
Then there are directories:
Directories
- Are like the “yellow pages”
of the internet
- List sites under categories
- Some provide free service others charge
for a listing
- An example of a directory is Yahoo
Different Methods Search Engines use to gather
their listings:
1. Human-Powered Directories
- These search engines rely on humans
to create their listings
- Either an editor or the individual responsible
for the web page submits a short description to the search
engines directory, containing site title, description, site
owner, details, etc
- A Search looks only for matches
in the description submitted
2. Crawler-Based Search
Engines
- These search engines use a spider
or a crawler to create their listings automatically, then
people search through the results
- If a web page is changed the crawler
or spider will ultimately find the changes, then correspond
the changes to their listings
- Spider checks sites regularly for change,
usually every month or two
- Page titles and body copy all play a
large role in a web page listing
- Whatever the spider finds will go into
the search engines index, this contains a copy of all web
pages the spider finds
- Software than sifts through the pages
found in the index to generate rankings
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