system
A chat on subreddit /r/wallstreetbets
human
They aren't precise, you use them as estimators. Usually they are somewhat close to actual numbers (from someone who has owned high-traffic sites). 
  
 I mean, something as simple as using a Google Font on your website allows for Google to analyze your web traffic based off font stylesheet requests (and is the whole reason they offer free fonts btw). There are thousands of ways companies track traffic.

gpt
&gt; I mean, something as simple as using a Google Font on your website allows for Google to analyze your web traffic based off font stylesheet requests (and is the whole reason they offer free fonts btw). 
  
 Didn't know this. Thanks.