What exactly is "Class C" and how do you check/verify it?

[Kush]

Originally posted by Cleo
Does Google even know what Class C address you are on?

I've always understood that Class C was always only used for private addressing.

See, I don't know.

I'm wondering if people say they have sites on different Class C's just to make their trading of links appear to be more valuable, or if it really does make a different.

I guess in some sense this is similar to people saying they have sites on different IPs. Is it really an advantage?