Click-Through Rate (CTR)
Definition
The percentage of users who click on an ad or email link after seeing it. A higher CTR indicates more effective messaging.
Example Use Case
A retail brand A/B tests two Facebook ads with different headlines to determine which drives more clicks.
Click-through rate is clicks divided by impressions, and it answers a narrow but important question: did the offer earn attention from the people who saw it? Because it is a ratio, it allows fair comparison between campaigns of very different sizes.
Read it as a diagnostic rather than a goal. A high CTR with poor conversion usually means the ad overpromised relative to the landing page, which is worse for the business than a lower CTR that converts. In search advertising, CTR also feeds into quality scoring, so relevance affects both the cost and the position you pay for.
The number is heavily context-dependent. A well-targeted email to an opted-in list and a broad display impression produce very different norms, so benchmarks are only meaningful against your own history and your own channel.
