When we talk about search engines, we usually mean web sites where millions or
even billions of querries are processed online every day. These search-database
service providers include AlltheWeb, AltaVista, AskJeep, AOL Search, Google, MSN
Search, Yahoo! and so forth.
As far as site
submission is concerned, the phrase search engine actually refers to both the
search directory (like business phone directory or yellow pages with categories)
and the the listing provider, and we don't really bother to distinguish one from
the other. The former definition includes Goto, ODP and Yahoo! And
the other definition includes Google and Looksmart.
In addition, the phrase search engine also refers to
the spider (or crawler). It is also called robot. But it's not really
a robot per se as you talk about its function. It is software that is used
to index websites on the web. (Read 'History to search engines.')
Yahoo uses Inktomi's Slurp. Google has Googlebot. And MSN Search uses
MSNBot. The spider travels from one site to another by following links given
by html tags like 'a href=' and 'img src' and goes back to the index database
to store the site information it has collected.
So how often does the spider visit your web site?
Some spiders visit your web site as often as you request it to with a meta tag.
Some never will once they show up. How can you tell when a spider or which
spider visited your web site? Your web hosting service may allows you to
check statistics of the activity on your homepage.
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