Quality Score is a metric used by advertising platforms (e.g., Google Ads) to assess the quality and relevance of ads, keywords, and landing pages. A higher score leads to a better ad position and a lower cost per click. It is evaluated based on the expected click-through rate, the relevance of the ad to the searched phrase, and the quality of the landing page. Improving Quality Score is fundamental to an effective PPC campaign and maximizes return on investment.