The dress was a 2015 online viral phenomenon centred on a photograph of a dress. Viewers disagreed on whether the dress was blue and black or white and gold. The phenomenon revealed differences in human colour perception and became the subject of scientific investigations into neuroscience and vision science.
I still don’t understand this. You can literally use a colour picker and see the colours are gold and very pale blue (almost white). That’s what the photo shows. It’s not a checkerboard illusion.