What Is an Algorithm, as It Pertains to Search Engine Marketing?

An algorithm, as it relates to search engine marketing (SEM), is a defined set of criteria and instructions that search engines use to rank websites based on their relevancy for keywords, key phrases, and search terms.

As of May 2014, Google owns a whopping 67.6% of the search engine market share. The second biggest search engine was Bing, which only owns 18.7% of the search engine market share. Naturally, this makes Google's patented PageRank algorithm the most important one in the SEM industry.

As a result of Google's sheer dominance in the SEM industry, most marketers gear their search engine optimization (SEO) efforts towards the PageRank algorithm, making sure sites fall within the lines of its guidelines. The more optimized a site is, the better the rank that Google's algorithm will give it. The better the rank, the more traffic the site will get. Search Engine Watch reported last year that the top listed result on Google's search engine results pages (SERPs) gets 33% of traffic, while second rank only gets 18%, with the percentages decreasing exponentially from there.

If sites don't comply with Google's SEO guidelines, they're liable to get penalized, which will cause their ranking to plummet, burying the site on Google's SERPs, where they won't get any traffic.