Impressions shows the total search volume of keywords for which a website ranks in the top 10. This is different to the way impressions is calculated in GSC.
How to use the Impressions metric?
Investigating the cause for drops in traffic. Sometimes you may see drop in organic traffic for a website, even though the website is not losing ranking positions in the top 10. With impressions, it becomes much easier to see if the drop in traffic is actually due to people simply making less searches for keywords your website ranks for.
Monitor brand awareness. If your website starts ranking in the top 10 for more high volume keywords over time, the Impressions metric will reflect it accordingly. Even if there is not a large increase in traffic, having your website show up in the top 10 positions for popular queries can give more overall visibility to your company and brand.
Where can you find the impressions of a website?
This metric is available in the Performance graph on both the General and Organic search views on Site Explorer > Overview.
In the General view:
In the Organic search view:
Can I see a website's GSC impressions in Ahrefs?
You can in Rank Tracker, but only for websites that you've verified ownership using GSC.
Learn more about how to view and analyze GSC data in Rank Tracker.