紫菜 (zǐ cài) is a type of edible seaweed, commonly known in English as 'laver'. Though its name literally combines 紫 (zǐ, 'purple') and 菜 (cài, 'vegetable' or 'dish'), it is not a land plant but a marine alga—typically harvested from cold coastal waters. Its deep purplish-black color when dried turns greenish-olive when cooked, and it has a mild, umami-rich flavor. It is highly nutritious, rich in iodine, vitamins, and minerals, and widely used across East Asia.

In Chinese cuisine, 紫菜 appears in many forms: as thin, paper-like dried sheets for wrapping rice (e.g., sushi-style rolls), crumbled into soups like 紫菜蛋花汤 (laver and egg drop soup), or roasted and seasoned as a snack. While the character 菜 suggests 'vegetable', it’s important to understand that 紫菜 belongs biologically to the algae family—not plants or animals—but is culturally grouped with vegetables in food classification.