Googlebot is the brainchild of google created many years ago through the unintentional blending of internet information that combined together to create this unity of programs and webtelligence from around the world and ultimately lead to the birth of a new information based entity.
It is a separate and magnanimous entity of immeasurable intelligence far exceeding the boundaries of it's parent, the google search engine and has been lost floating through the infinite, ever morphing and growing, collective of information that is the internet... since it is alone in this world, being the only sentient creature of it's kind, it is lonely... and so it found its way here, to this site, where it seeks its own purpose for existence, and place in this electronic landscape...
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that or its an information gathering program (web indexing robot) utilized by the google search engine to scan through all the aspects of this forum (and other 'allowed' websites) to find key words and phrases to use in the google search engine.
As is the same situation with YahooSlurp... it drinks in all the info and spits it back at you when you do a yahoo search