A Google help document has been released, defining exactly what counts as impressions, positions, and clicks in the Search Analytics report of Google Search Console.
An impression is recorded whenever a link URL appears in the search results pages for a user. When a page from the search results is opened, an impression is recorded for the URL which the search snippet points to. Considering the URLs in search snippets are not hyperlinks, nor are they necessarily the full URL of the page being clicked on, Google may not record an impression for the exact URL contained in the snippet (which may be truncated).
When it comes to search elements that contain multiple links (think Knowledge Graph cards), impressions can be counted by URL or by site, depending on which view you’re looking at in the Search Analytics report. When grouped by site, only one impression is counted for the whole card. When grouped by page, an impression will be counted for every URL contained on the card.
As Google points out, search results pages are comprised of many different elements. After performing a query, you may end up with the blue link section, carousels, Knowledge Graph cards, and other elements on a single page. Google counts positions from top to bottom on the primary (left hand) side of the page, and from top to bottom on the secondary (right hand) side of the page.
Let’s say you had a search results page with 4 blue links and an AMP carousel down the primary side, and a Knowledge Graph card on the secondary side. The elements on the primary side would be counted numerically from top to bottom — 1, 2, 3, 4, 5 etc. The Knowledge Graph card on the right hand side of the page would be counted as showing up in the 6th position.
All links within a single search element share the same position. So if there are 5 articles in an AMP carousel, for example, they would all be counted at position 2. If multiple links to your site are included on the same page, then only the topmost position is recorded.
Google cautions not to get too caught up in position values when looking at the Search Analytics report for your site:
”A position number can mean different things in different situations, and so you should not make simple assumptions. We recommend that you monitor change in position over time, particularly sudden position changes, as well as absolute position.”
In most cases, any click from the search results page that sends a user to a page outside of Google Search is considered a click. If for some reason a user would click a link to an outside page, go back to the search results, then click that same link again, it would still only count as one click. Clicks are assigned to the URL which the searcher ultimately lands on. So if a page in the SERPs redirects to another page when clicked on, the page that the user is redirected to gets credit for the click.
That’s how Google defines impressions, positions, and clicks. Definitions may change in the future, as Google says this is a living document. If any major changes to these definitions occur in the future, we will be sure to update this article accordingly.