There are many things in life that require a double-take.
A person who you thought you recognized in a crowd, spotting a store you want to check out, or recreating that meme of that boyfriend who checks out another girl while his girlfriend looks on, furious.
Miraculously, people have been able to capture these photos for the internet to see.
So whether it's a perfectly-timed photo or unique things no one noticed before, here are 19 times people had to do a double-take.