Visibility on the Web is important for many people and commercial organisations as for many it has become one of the key issues for successful business. Most of the visibility is obtained through top rankings in search engine results. Simultaneously the end users have begun to rely more and more on search engines to locate the content they seek as finding information otherwise on the Web has become notoriously difficult. These issues have lead to an increased interest on search engine results as the top results gain more visitors than others. Due to importance of visibility, many companies...