I was browsing the internet the other day and came across a site known as spur.us. The site claims to "Stops fraud and abuse on the internet" by collecting and indexing IP usage, VPN IPs, and proxy IPs.
Its a very interesting site, you can get info on any IP by visiting spur.us/context/youriphere. My question is, how does it work? How does a site collect data on every IP address out there? How do they know that X amount of people are on my IP address? How do they know that I have connected to the Tor network or used ProtonVPN?