Introduction: Defying Physics
If you log in from London at 10 AM and then from Los Angeles at 10:15 AM, you have defied the laws of physics. Unless you have a teleportation machine, it’s impossible to travel that far in 15 minutes. In cybersecurity, this is called Traveling IP Logic (or 'Impossible Travel').
The Algorithm
Security algorithms calculate the distance between your last two IP addresses and the time between the logins. If the 'Speed' required to get from Point A to Point B is faster than a commercial jet, the system flags the second login as a hack attempt.
Conclusion
Geography is a powerful security tool. By using common sense and IP data, websites can spot fake logins with incredible accuracy. Check your travel logs here.