The term "search engine" is often used generically to describe both
crawler-based search engines and human-powered directories. These two
types of search engines gather their listings in radically different
ways.
Crawler-Based Search Engines
Crawler-based
search engines, such as Google, create their listings automatically.
They "crawl" or "spider" the web, then people search through what they
have found.
If you change your web pages, crawler-based search
engines eventually find these changes, and that can affect how you are
listed. Page titles, body copy and other elements all play a role.
Human-Powered Directories
A
human-powered directory, such as the Open Directory, depends on humans
for its listings. You submit a short description to the directory for
your entire site, or editors write one for sites they review. A search
looks for matches only in the descriptions submitted.
Changing
your web pages has no effect on your listing. Things that are useful for
improving a listing with a search engine have nothing to do with
improving a listing in a directory. The only exception is that a good
site, with good content, might be more likely to get reviewed for free
than a poor site.
"Hybrid Search Engines" Or Mixed Results
In
the web's early days, it used to be that a search engine either
presented crawler-based results or human-powered listings. Today, it
extremely common for both types of results to be presented. Usually, a
hybrid search engine will favor one type of listings over another. For
example, MSN Search is more likely to present human-powered listings
from LookSmart. However, it does also present crawler-based results (as
provided by Inktomi), especially for more obscure queries
Example of 5 search engines on the Internet
2. http://www.azoos.com/
3. http://www.chacha.com/
4. http://iboogie.com/
5. http://www.qwiki.com/
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