Google Photo Everything

Got a message from the guy I sold my 2009 Macbook Air to back in 2013. He needed the serial number because it was stolen and I'm not one to let justice go unanswered, so I pulled up my Google Photo library and searched "Macbook" and BAM, the photos I used for the Ebay sale popped up and I was able to get the serial number. Quite amazingly scary how effective Google search can be in my online persona.