Quality Score

A Quality Score is a metric Google uses to determine where advertisers rank. The score serves as a check against rule by budget alone, by requiring advertisers to prove their relevance. More relevant ads generally get higher click-through rates (CTR), so CTR is one of the major components of Quality Score. Other factors that may also influence the Quality Score include: landing page quality, your historical account performance, the relevance of your keyword to its ad group, and the relevance of your ad text.

Based on what keywords you are bidding on and what match types you are using, Google calculates a score between 1 and 10 for your ad. The higher your score, the better your ad rank will be. A high Quality Score can even qualify you to rank above people who are bidding more than you. Another major component of Quality Score is that it has an enormous effect on how much you pay when someone clicks your ad.