Google's Quality Review and Search Engine Optimization Guidelines
There are different types of quality reviews of websites. From Google's perspective, most things are done algorithmically by the search engines. But Google has one patent how manual review affects search results. I have also met people who have worked with quality review at both Google and Bing, although it seems that most of this work is outsourced and outside the companies' core business.
In the Swedish market, as long as until 2014, no one sat and quality-checked the Swedish market from Google's European headquarters in Dublin. Of course, there are many Swedes who work at Google and when I talked to Sweden the head of Google was the official position that Google wants a clear line between the purchased and organic search. In the Swedish office, no one officially worked actively with SEO or search engine optimization review.
Google Quality Rater Guidelines - Official Quality Guides
There were long rumors about quality guides and in the spring of 2015, a quality review document was leaked from Google. On November 19, 2015, Google released a new one the quality review document which was then updated and was 160 pages long.
On July 20, 2018, it was time again and then the document was updated with the title General Guidelines. Now the document was 164 pages long. A few days later, on August 1, after the update, Google made a filter update "Medic Update" which was a core update of Google's algorithm. It got many companies to start looking at the document as well as the previous advice that came from former Google CEO Amit Singhal in connection with Google's Panda update which was launched in May 2011.
There is also one official document from Google on SEO for webmasters on how to build quality sites. All websites have a purpose for the creation of the page and in order to be able to do a good review, the quality reviewer needs to understand the purpose because there are different requirements depending on the purpose of the website. Pages that affect human health and finances are called YMYL ("Your Money or Your Live”) Where the requirements are set higher than for ordinary pages.
When Google does its reviews, the EAT formula is used. The document itself is a fairly dry and long document that is a support for the quality reviewers when they are to examine the site's reputation and that there is a clear sender.
A new quality document was released in October 2015
Since the first quality review document leaked, a lot has happened with the algorithm (Rankbrain) and new filters have been introduced. A new quality document was leaked in October 2015 which was updated. Above all, factors surrounding mobility and the search for premises have changed.
Google Official Guidelines