A moderately-sized rectangular gap between clothing that exposes the character's stomach. The total amount of exposed skin should equal no more than half the stomach’s surface; with waistline bottomwear the gap ends slightly above the navel, though it can shift to accommodate high-waist clothing.
Use midriff when there are regular clothes above (e.g. a crop top) and below (e.g. pants) the stomach, but the stomach is bare or visible beneath see-through clothing. Not limited to things that exist in real life, but all swimsuits and underwear such as bras and panties are excluded unless they're visible beneath normal clothing.
Don't use this tag if the character is topless, bottomless, nude, or wearing only underwear or a bikini. Exceptions include underwear worn as outerwear, such as sports bras, camisoles, tank tops worn with panties, or similar.