What Is Co-Citation and Co-Occurrence

Co-citation and co-occurrence are two of the major terms in the SEO sphere –concepts on which Google’s next search engine strategy will evolve. Google will then dismiss backlinks as a ranking factor and will center all updates of its algorithms to these two.

Google wants to provide users with the most valuable, useful and accurate information. Thus, it keeps on improving its algorithm methods. According to Google’s Amit Singhal, Search is similar to the perfect loyal assistant in Star Trek, always there when needed.

Co-citation and co-occurrence are two different things, yet they are oftentimes discussed together.


When a website is mentioned or referenced by two or more sources, co-citation happens, even if there is no linking involved. It is called back linking without links.

As more websites refer to a certain site, and not even linking, either indirect or pure incidental, the site mentioned will have its authority established and may prominently rank in Search Engines Results Pages.

Co-citation is like telling Google algorithm that the mentioned website is important and relevant. The three websites – the one mentioned and the two which mention it are related.

It is just like celebrities mentioning more famous stars to expand their fanbase; or rubbing shoulders with thought niche leaders can establish oneself as a significant elite member.


Co-occurrence refers to the frequency of occurrence of the same keywords that are present on websites. It includes keywords on the same topic, or similar to each other, but not exactly the same.

Co-occurrence started when search engines throw out “relevant answers” to a query. The aftermath of Google’s Hummingbird update has SEO specialists focusing on ideas, answers and questions, not keywords. When a website contains keywords for which webmasters wish it would be ranked, search engines will check the website. If it sees the site’s keywords as relevant, it will display the site in the results.

Co-occurrence is not dependent on links completely, but great content which mentions keywords that can propel the site to prominence. Co-occurrence occurs when more search queries are similar in terms, especially if they are consecutively searched for.

For example, when people search for “Baby crib Amazon” and “used baby crib for sale,” Google will interlink the terms and conclude that when people search for baby cribs in Amazon, they are looking for used baby cribs for sale. The connection between these two key phrases become more enhanced and related if many use them, even if they have different search terms and contexts.

Rankings by Search Engines

In the past, people have manipulated anchor text to improve the rankings of their websites, but Google penalized them when caught. Co-citation and co-occurrence are Google’s way to avoid SERP manipulation, countering over-optimization, which is why Google Penguin was introduced.

Both co-citation and co-occurrence are achievable only if the content on the website is valuable enough – worthy of mention and sharing. These two will be the future fundamentals to determine website rankings.

The key factor is to create quality content in websites and be steadily active on the net, such as being active on discussion boards, forums and writing more trending topics for people to “cite.”

Image courtesy of Danard VincenteFlickr