One of the Major Arcana defined in tarot. In typical portrayals, the Sun is a scene of a naked child (in this sense, the child is innocent and represents having nothing to hide) riding atop a white horse in the open sun, with a bunch of sunflowers visible in the background.

In cartomancy, the upright Sun arcanum is interpreted as positivity, fun, warmth, success, and vitality.
The reversed Sun arcanum is interpreted as one's inner child, feeling down, and being overly optimistic.