This comic shows two drawings of a woman wearing the same dress, but with different background (and body) colors. The two drawings are split with a narrow vertical portion of an image from the web.
The comic strip refers to a dress whose image went viral on Tumblr only hours before the strip was posted and soon showed up also on Reddit, Twitter, Wired and on The New York Times.
Due to the dress's particular color scheme and the exposure of the photo, it forms an optical illusion causing viewers to disagree on what color the dress actually seems to be. The xkcd strip sandwiches a cropped segment of the photographed dress between two drawings which use the colors from the image against different backgrounds, leading the eye to interpret the white balance differently, demonstrating how the dress can appear different colors depending on context and the viewer's previous experiences.
Both dresses have exactly the same colors actually: //
To the uninitiated, the color of the dress seems immediately obvious; when others cannot see it their way, it can be a surreal (even uncomfortable) experience.
As an aside, the retailer Roman Originals would later confirm the dress was blue with black lace, and that a white dress with gold lace was not offered among the clothing line.
