Click-through rate (CTR)(CTR)

Click-through rate (CTR) is the share of impressions that earn a click: CTR = clicks ÷ impressions (often shown as a percentage). It signals creative/message fit and auction competitiveness on click-based inventory (Search, many social feed units). Low CTR can raise effective CPC in auctions that weight expected CTR; high CTR with weak downstream conversion may mean the ad over-promises.

Industry CTR varies wildly by channel — compare against your own historical baselines and placement mix, not generic blog benchmarks.