Don't remember, it was probably google image search (which I use a lot, looking for differences between model years of whatever has my attention for that moment).
I was (and am still) amazed by many members ability to diagnose the exact year and trim level of so many different vehicles given so little information. I'm not great at it, but after a few months lurking I saw there was enough information I could add to justify signing up. I'm glad I did, this is a really nice community.