What is SEO? Search Engine Optimisation (SEO) is the process of generating traffic from the 'free' or 'organic' search results page of a search engine such as Google or Bing. Marketers use SEO techniques to gain high ranks with the intention of driving higher traffic. Search Engine Marketing (SEM) is the process of generating website traffic from the search results page of a search engine such as Google or Bing by purchasing advertising. Purchasing advertising space increases the visibility of a website on a search engine irrespective of your organic rank.