Quality Score is a keyword-level diagnostic on a 1 to 10 scale built from three components: expected click-through rate, ad relevance, and landing page experience. Each is reported as Below Average, Average or Above Average, and those labels are the useful part. The reported score is not the number used in the live auction. Fix below-average expected CTR with keyword-matched pinned headlines and extensions, fix ad relevance with tighter ad group themes, and fix landing page experience with literal message match and faster mobile pages. Prioritise your highest-spend keywords first.