Capsicum is the genus of flowering plants that includes all sweet and hot peppers, from bell peppers to chili peppers, in the nightshade family Solanaceae. It is native to the Americas, with evidence of chili use in Mexico dating back roughly 7,500 years, and it spread worldwide after the Columbian Exchange.
In British, Australian, and Indian English, "capsicum" often refers specifically to the mild bell pepper, while American English typically calls the whole genus "pepper" and reserves "capsicum" for scientific or produce-import contexts.
Heat varies enormously across the genus and is measured on the Scoville scale, from mild bell peppers to fiery habanero peppers. Capsicum is essential across Mexican, Indian, Thai, and Mediterranean cooking, used fresh, roasted, stuffed, or ground into spice blends.