Google Webmaster SEO Starter Guide - Originally written for Google Employees to improve website performance with users and search engines. Related Terms: SERP - Search Engine Rank Position | PageRank (PR) - Named for Google Co-founder, Larry Page. The PR Scale of 0-10 rates a web page. In the past, rank was based on the number of high ranking links pointing to the website. Recently factors like relevance and quality have gained importance. This website's current PR rating: SEMrush is a very useful tool for both researching competitors when starting a site or for growing an established site. I really like to find weaker niche sites that still seem to be ranking for lots of keywords; SEMrush helps me see what they are ranking for and what I can potentially target. You can also see what keywords you’re on the cusp of ranking for with your established site - another very useful feature.
It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.