That mysterious inner flap, often mistaken for a pocket, is actually called a gusset, and it’s there for one crucial reason: protection. Sewn into the crotch of many pairs of underwear, the gusset adds an extra, usually cotton, layer where the body is most sensitive. This extra panel reduces friction in tight or synthetic underwear, helping to prevent irritation, chafing, and inflammation that can easily go unnoticed until it’s painful.

More importantly, the gusset is designed to breathe and absorb. By wicking away moisture and allowing airflow, it helps keep the genital area drier, which makes it harder for yeast and bacteria to thrive. It isn’t meant for storing anything and often isn’t fully sewn on one side simply due to how underwear is constructed. It’s a small, almost invisible detail, quietly doing an outsized job for your comfort and intimate health every single day.