If you frequently cook Chinese food, you know that your pantry requires extensive outfitting before you can whip out your wok. Chinese dishes can require anything from rice vinegar to oyster sauce and sesame oil, but the most common seasonings are dark and light soy sauce, which may look similar, but have unique uses.

Soy sauce, or jiàng yóu (酱油), is a made through a long process of brewing fermented soybeans plus mold or yeast. For the most part, when a recipe calls for just plain soy sauce, it’s likely referring to light soy sauce, which is popular in Cantonese cooking, and is lighter in color but saltier than dark soy sauce.

Dark soy sauce is noticeably thicker and sweeter than its light counterpart, meaning that they cannot be used interchangeably. When dark soy sauce is used, it’s often to add color and coat meats, rather than as an all-purpose seasoning. Whichever you use, remember to store it in your pantry, not your refrigerator.