Click-Through Rate
Click-through rate (CTR) is the percentage of people who clicked your ad after seeing it, calculated as clicks divided by impressions. In paid search it signals how compelling and relevant your ad copy is to the searcher and feeds directly into the expected CTR component of Quality Score.
Why It Matters
CTR is an early indicator of ad relevance and messaging fit. A strong CTR lifts Quality Score and Ad Rank, which lowers costs, while a weak CTR flags copy or targeting that is missing the searcher's intent.
Common Mistake
Optimizing for CTR in isolation. A clickbait headline can spike CTR while attracting unqualified clicks that never convert, raising spend and hurting cost per acquisition.