Anyone who thinks Google's results are solely the product of fancy-pants algorithms and clever engineering -- think again. The Register has taken a look into Google's 160-page guidebook which is essentially a reference manual for human "raters" -- yep, that's right: humans -- revealing a definite human component behind the results dished out by Google search.
As it turns out, Google outsources (i.e. entrusts) a couple of different crowdsourcing agencies -- Lionbridge and Leapforce -- to produce warm bodies and squeeze those human beings for their valuable opinions. The Register also points out that according to one Leapforce job ad, the company employs about 1,500 search assessors which is decidedly a work-from-home gig.
Before such contractors can judge the results doled out by Google search queries though, individuals must pass an initial examination. Afterwards, search assessors continue to receive periodic Google evaluations to ensure they're doing an upstanding job grading search results.
Google's manual, amongst other things, informs raters about how to rank search results based on a variety of metrics: quality, relevance and spamminess. Search assessors will judge the results for various queries and choose from any number of grades -- such responses include: "Not Spam", "Maybe Spam", "Porn", "Off-Topic", "Unratable", "Vital" and others.
Just to name a few esoteric guidelines, raters are asked to consider user intent (e.g. Mountain Lion: Mac OS X or the actual predator?), ignore websites with invalid security certificates and avoid results older than four months.
Check out this article for a deeper look into how humans help Google provide the best results possible.