Extended definition
Percentage of users who see your result in SERP and click. CTR depends on position, meta title, meta description, rich snippet presence.
Context and application
CTR is a dual-utility indicator: measures SEO performance (position + snippet attractiveness) and is also a ranking signal (Google detects abnormally low CTR for position = page seems irrelevant for query). In Google Search Console, filter on queries where you appear in position 1-3 with CTR under 10% — these are meta title + description optimization opportunities. For rich snippets (FAQ, Review, Product), CTR can grow 20-40% on the same position. That’s the direct ROI of correct schema markup implementation.
In practice
average CTR position 1 ≈ 27%, position 5 ≈ 6%, position 10 ≈ 2%.