Widely considered one of the world's oldest condiments, soy sauce is a fermented soy bean product. It was probably first discovered more than 3,500 years ago in China as part of the process of preserving fish. It's used in seafood, meat and vegetable dishes and as a base for other sauces, like teriyaki. It may also be the precursor of the ketchup we know and love today.
Soy sauce is available in a number of varieties: light, dark, low-sodium and blended. Blended soy-based sauces incorporate other Asian herbs and spices, like garlic, five-spice powder and ginger for added flavor.