Today the world argues amongst itself about the colours of a dress.
The split is caused by innate differences in how we all perceive colour. Here are some other illusions that will leave you scratching your head.
The dancer illusion
Stare at this gif. Then look at it again. What way is the dancer spinning?
The Dynamic Ebbinghaus
This won a best illusion of the year contest in 2014. The circle in the middle stays the same size but looks different because the circles around it are dynamic.
The Purple Nurple
This is not a gif - it's a static image.
How many legs do you think this elephant has?
The silencing illusion
Play this video while looking at the small white speck in the centre. When the ring begins to turn, the dots look like they stop changing colour. Actually they are still changing.
As strange as it sounds, square A and square B are exactly the same colour.
The McCollough effect
After looking at the lines for 15 minutes, the brain will see the opposite of these colours once the lines have disappeared - this is known as the McCollough effect.
The duck-rabbit illusion
The famous duck-rabbit illusion was first popularised by American psychologist Joseph Jastrow who showed that the brain cannot see both images at once. The participant usually sees just one of the animals when they first view the image but after being told of the others existence they then flicker between the two - again being unable to un-see the second image. Which reminds us of something...