It refers to the importance of information to a given user.

It is very important for any user to know how much relevant is his/her ads, website and keywords are. To encourage relevancy and higher quality ads, Google has recently introduced Quality Score that will have an affect on your ads costs and performance. Relevancy in general indicates how important are things like landing page, keywords, and ads and so on. They are also closely associated with quality and measured by Quality Score. Based on the relevancy of the users’ ads, success in advertising can be achieved. In general, there are two types of Quality Scores – Ad Quality Scores and Keyword Quality Scores.