It is a form of measurement that is most commonly employed for search engine optimization and that pertains to the amount of page targeting and offsite link building required. More commonly referred to as KPI, keyword difficulty is mostly ranked on a scale of 1-100. As per this scale, a search phrase which requires comparatively more efforts, and consequently a high keyword difficulty will be given a score more towards 100 while a search that requires much less effort will be given a score close to one.