What cause Core Ranking Algorithm Behind The Fluctuations?

[Marvin]

please answer thanks

[Jesse001]

Google has made a massive change to the way it ranks websites. How massive? This change outranks both Panda and Penguin in terms of its scale of impact on search results, according to Google's Webmaster Trends analyst Zineb Ait Bahajji.

[Angela]

Google ranking algorithm called PageRank and developed by Google founders Larry Page and Sergey Brin at Stanford University. This is the core of the Google rankings even if a lot of other aspects will affect the rankings. Here is how Google determines their PageRank algorithm:
PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of the value of an individual page. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at much more than the sheer volume of votes, or links a page receives; for example, also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important." Using these and other factors, Google provides views on the relative importance of pages'.

[Nicolos]

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They determine which websites are most useful and relevant by using a complex algorithm (a mathematical process) that takes into account the 200+ different factors.
Google does not let people know what the factors are, however, through a combination of research, testing and experience, Google SEO consultant who well know what is the most important factor. For example, most SEO will agree that the following are all important ranking factors ...
The use of keywords
Site structure
Site speed
Time spent on site
The number of inbound links
Quality inbound links
This algorithm is designed and set-up by humans, however, the ratings are given to sites that are completely determined by the results of the algorithm. No manual intervention by humans to adjust the rating of certain web sites provided by the algorithm.