Cats With Fur Heart

In Code page 437, the original character set of the IBM PC, the value of 3 (hexadecimal 03) represents the heart symbol. This value is shared with the non-printing ETX control character, which overrides it in many contexts.
Mathematical description
There are several mathematical descriptions that result in approximately heart-shaped curves. The best-known of these is the cardioid, which is an epicycloid with one cusp. The implicit curve (x2+y2-1)3-x2y3=0 yields a better approximation of the heart shape.