Google contracts with over 10,000 search quality raters worldwide to evaluate its search results. Raters are given actual searches to conduct, drawn from real searches that happen on Google. They then rate the quality of pages that appear in the top results � hence the �quality rater� name.
Quality raters cannot alter Google�s results directly. A rater marking a particular listing as low quality will not cause that page to be banned or lose ranking.
Instead, the data generated by quality raters is used to improve Google�s search algorithms, an automated system of ranking pages. Over time, that quality rater data might have an impact on low-quality pages that are spotted by raters, but the algorithm will also impact pages weren�t reviewed.
Quality raters use a set of guidelines you can see here that are about 200 pages long, instructing them on how to assess website quality and whether the results they review meet the needs of those who perform searches.
2017 Guide: http://bit.ly/1ZdLFyy
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