Search Engine Optimization (SEO) is a very important aspect for any company that wishes to attract customers via online channels, particularly when the vast majority of internet users resort to Google searches in order to find what they are looking for.

Some great tips are covered in the extensive article by Minda Zetlin, How to Improve Your Site’s Search Engine Optimization, which focuses first on explaining some methods behind Google’s page ranking.

As outlined in the paper entitled The $25,000,000,000 EigenVector, The Linear Algebra Behind Google, there are three key steps behind all search engines:

1. Crawl the web and locate all web pages with public access.

2. Index the data from step 1, so that it can be searched efficiently for relevant keywords or phrases.

3. Rate the importance of each page in the database, so that when a user does a search and the subset of pages in the database with the desired information has been found, the more important pages can be presented first.

The reason why Google returns better results than other search engines, particularly in the early stages of search engine development, is because it goes beyond matching the searched text with page content and ranks website based on their ‘citations’ on other websites.

This means that given two webpages with identical content, the one that is cited by 100 other reputable websites will rank much higher than the one that is ranked by 100 ‘shady’ websites. The whole concept comes back to a measure of ‘influence’, or centrality, known as EigenVector and which is extensively used in the area of Social Network Analysis (SNA). Based on this calculation method, a page’s centrality (or relevance) is a function of its ties to other sources as well as the other sources’ ties to other sources.

This concept is illustrated in the following image: Webpage A has three links to other websites while webpages B, C and D have four links to other websites. In this case, even though webpage A is cited fewer times (3 < 4), it may actually rank more highly since it is cited by pages B, C and D which all have 4 links.

This short example of EigenVector centrality highlights a key business and SEO take-away: linking your website with fewer very reputable websites may increase your ranking significantly more than being cited by hundreds of obscure/less reputable sites.