Google Search Console is a free tool from Google for website owners. It shows the searches your pages appear for, your clicks, impressions, average positions and click-through rates, and reports indexing and technical problems.
Why it matters
It's the most direct source of truth about how Google sees your site. Third-party tools estimate; Search Console shows your actual performance.
Example
Search Console might show that a page gets 5,000 impressions a month at position 9 but only 40 clicks. That's a page worth improving, because a small ranking gain could bring many more visits.
What to do
Verify your site, submit your sitemap, and check it regularly for pages losing clicks, searches you almost rank for, and indexing errors.