The two main types of soy sauce are light and dark. As the name implies, light soy sauce is lighter in color, and also more sweet than dark soy sauce. In Chinese cooking, it is used more often than dark soy - always use light soy in a recipe unless dark is specifically called for. Aged for a longer period of time, dark soy sauce is thicker and blacker in color. It is also less salty than light soy.