How I pretend search engines rank sites

I like to think of the ranking of a site in search engines to be a conceptual formula. This is not how search engines actually rank a site or page, but pretending it does it this way helps understand what needs to be done:

Ranking = relevance x importance +/- quality

A number of factors go into the relevance, importance and quality scores. Different search engines such as Google, Yahoo! and Bing) will weight those factors differently and the weighting given to each factor will change over time. Some of the factors used to carry a lot of weight in the past and these days do not carry much weight (spammers or abusers of these factors made sure that the search engines devalued that factor). Because of the changes in the weighting of these factors, a sites ranking will change with time.

The first thing a search engine has to do is determine if a site is relevant to a particular search query. It could determine a sites relevance from one, some or all of the following factors:

1.    The keyword in the title of the page (the early in the title the word is, the more relevant)
2.    The keyword in the meta keyword tags
3.    The keyword in the meta description
4.    The keyword in the H1, H2 tags
5.    The keyword is mentioned often on the page (keyword density)
6.    The keyword is in bold and italics somewhere on the page
7.    The keyword is in the alt tag of images
8.    The keyword is in the anchor text of internal links and external backlinks
9.    The keyword is in the URL of the page
10. The keyword is near the start of the first paragraph

To determine relevancy a search engine will analyze some of these. It is generally considered that the title of the page and the anchor text of backlinks perhaps carry the most weight with Google.

Once a search engine has determined a page is relevant to a search query, it then has to decide what order to rank the pages (site) in the SERPs (search engine results page). They generally determine importance by looking at the number of backlinks to a site. Some backlinks will carry more weight than others in their importance score (link juice). For example, backlinks to a site that were given editorially from a pages that the search engines already consider important will carry a lot more weight than links that are easily gained by self promotion, such as from web directories, social bookmarking and article submission. Google uses its PageRank (PR) algorithm to determine the importance of a page, but just how much weighting this importance is given relative to the relevance score is not clear and changes with time. Bing have their Page Score which is a measure of how authoritative they see a site. The authority status of a backlink and the trust (see mozTrust) also play a role.

Unfortunately,  just the importance x relevance does not always explain the ranking of a site, so conceptually a quality score comes into it. They look for things on a site that might indicate high quality versus low quality. Low quality signs might include participation in link exchange schemes; a very high number of low quality links relative to the high quality editorially gained links; a high number of links from the same IP address; the unnatural use of text on a site; hidden text and links; etc. High quality signs might be a wide range of types of links from a wide variety of IP addresses and from what the search engines consider authority sites; the site is listed in DMOZ or other important web directories.

Like I said as the start, this is probably not how the search engines rank sites, but is a good way to understand it and get a good idea where to start. To learn more about SEO or search engine optimization see this: New to SEO (search engine optimization)?

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