The Cool S, also known as the Universal S, is a graffiti sign in popular culture that is typically doodled on children's notebooks or graffitied on walls. The exact origin of the Cool S is unknown,[1] but it became prevalent around the early 1970s as a part of graffiti culture.[2][3]
The Cool S consists of 14 line segments, forming a stylized, pointed S-shape. It has also been compared to the infinity symbol.[4] The tails (pointy ends) of the S appear to link underneath so that it loops around on itself in the same way as the infinity symbol does.[5] The Cool S has no reflection symmetry, but has 2-fold rotational symmetry.