Where do websites get traffic and search analytics information from?

Question

Search Engine Optimization

I was interested in the question of where various sites come from, where the user simply indicates the domain and fairly detailed statistics are issued on it, they draw information. For example, semrush.ru generates fairly accurate search traffic.
Thank you.

Answer 1

Google is parsed, information about the positions of sites is collected. Further, knowing the positions and the number of search queries for keywords, it is not difficult to calculate the approximate traffic to the site.