Retrieval and Rankings

The next step in this quest for knowledge occurs when the search engine returns a list of relevant pages on the Web in the order most likely to satisfy the user. This process requires the search engines to scour their corpus of billions of documents and do two things: first, return only the results that are related to the searcher’s query; and second, rank the results in order of perceived importance (taking into account the trust and authority associated with the site). It is both relevance and importance that the process of SEO is meant to influence.



Relevance is the degree to which the content of the documents returned in a search matches the user’s query intention and terms. The relevance of a document increases if the terms or phrase queried by the user occurs multiple times and shows up in the title of the work or in important headlines or subheads, or if links to the page come from relevant pages and use relevant anchor text.

You can think of relevance as the first step to being “in the game.” If you are not relevant to a query, the search engine does not consider you for inclusion in the search results for that query.

Importance or popularity refers to the relative importance, measured via citation (the act of one work referencing another, as often occurs in academic and business documents) of a given document that matches the user’s query. The popularity of a given document increases with every other document that references it. In the academic world, this concept is known as citation analysis.

You can think of importance as a way to determine which page, from a group of equally relevant pages, shows up first in the search results, which is second, and so forth. The relative authority of the site, and the trust the search engine has in it, are significant parts of this determination. Of course, the equation is a bit more complex than this and not all pages are equally relevant. Ultimately, it is the combination of relevance and importance that determines the ranking order.

Popularity and relevance aren’t determined manually (those trillions of man-hours would require Earth’s entire population as a workforce). Instead, the engines craft careful, mathematical equations—algorithms—to sort the wheat from the chaff and to then rank the wheat in order of quality. These algorithms often comprise hundreds of components. In the search marketing field, they are often referred to as ranking factors or algorithmic ranking criteria.