My impression is that, when I hit Stack Overflow for the first time, it records my IP address as a user since I can ask a question without being logged in, in the traditional sense, but I'm still tracked.
Is this what SO does? Base a non-logged in user as an IP address? Or is it a combination of cookies/sessions and IP?
I want to implement a similar solution, but I'm afraid of IP modification and users faking an IP to obtain another user's account. How should I handle this?