The Dress is a viral photo showing a garment that different viewers perceive as different colors. Some saw it as blue and black, while others saw it as white and gold. The trend demonstrated how individual perception varies based on optical properties and assumptions about lighting conditions. The image became instantly memetic not because it was funny, but because it was genuinely confusing and sparked passionate debate. Scientists later explained that the ambiguous lighting and the observer's brain's assumptions about lighting conditions affected color perception.

The photo was originally of a dress someone was considering purchasing and posted to Tumblr for advice. The image's ambiguous lighting created an optical illusion where viewers genuinely perceived different colors. The moment went viral when millions of people became engaged in the debate. Neural scientists explained that the brain's interpretation of light sources affected color perception, those assuming cool lighting saw blue/black, while those assuming warm lighting saw white/gold. The genuine optical illusion made it notable compared to most internet moments.

The Dress demonstrated how powerful collective internet attention on ambiguous events. The event showed how the entire internet could focus on a single question and engage in meaningful debate. Scientists used the craze to explain optical perception and how brains construct reality. The Dress remains notable for being a rare moment where meme culture engaged with a genuine scientific sensation rather than created content. The event grew into part of internet history and is frequently referenced.