Click-Through Rate (Search)
Search click-through rate (CTR) is the percentage of search queries where the shopper clicked at least one result, used as a proxy for whether the results returned looked relevant.
Part of Search Analytics
A low CTR on a high-volume query is a common signal that something is wrong with the results for that query — even when the search technically returned products, since a zero-result query trivially has zero CTR by definition and doesn't need this metric to flag it.