Quality Score is Google's rating of the quality and relevance of both your keywords and PPC ads. Quality Score is an estimate of the quality of your ads, keywords, and landing pages.
Quality score is a score that provides through PPC to your ads.
It dependent on relevant keywords, landing page, ads title and CTR (click through rate).
To reiterate, your AdWords Quality Score depends on several factors, among them:
- The relevance of your ad to the keyword.
- The relevance of your ad to your landing page.
- The historical performance of your account.
- The click-through rate of your ad.