Number of pages classified by research motors for one (couple of) keywords(s). Coupled with a qualitative analysis of pages put in first position of the results of research motors on your requests, it determines the feasibility of a positioning: the more competition is big and the more PageRank ™ of the "leader" is well brought up, the more positioning is difficult. Every motor displays the competition linked to grabbed request, at the head of its pages of results. Each of them has his own way to index Web pages; the competition for the same request is variable from a motor to the other one.