Definition
A SERP (search engine results page) is the page Google, Bing or another search engine shows after you enter a query. It used to be a list of ten blue links; today it is a composed page with organic results, ads, a featured snippet, People Also Ask, images, videos, a local map pack, shopping results and, increasingly, an AI answer at the top.
Every query gets its own composition. For an informational question ('what is a canonical url') you often see an AI Overview or a snippet followed by guides; for a purchase question ('buy garden chair') shopping blocks and category pages dominate; for a local question ('dentist utrecht') the map pack sits at the top. The composition therefore tells you which intent Google suspects behind the query and which type of page stands a chance.
For SEO, the SERP is the playing field. A position is only valuable in the context of what surrounds it: position 1 below an AI Overview and three ads delivers fewer clicks than position 1 on a bare page. That is why at Traze we do not only look at rankings, but at the share of visibility across the whole page, including the AI answer and the sources it names.
The SERP also changes per country, language, device and even per person. So you always measure with a fixed combination of keyword, country and device, repeated over time. That way you can tell whether a shift in clicks comes from your own position or from a new feature Google has placed at the top.