Tofu is prepared by coagulating soy milk and pressing the resulting curds into a solid block of varying softness (silken, soft, firm, extra firm etc). Tofu has a muted flavor, that can be used in both sweet and savory recipes. Tofu is low in calories, and is a rich source of protein, iron and calcium (if the tofu was calcium-set).
Tofu is set using a variety of coagulants, like gypsum (calcium sulfate), which produces tofu that is tender but brittle in texture, and chloride-type nigari salts (magnesium chloride and calcium chloride), which produces tofu with a smooth and tender texture.
There are many types of processed tofu, including pickled tofu (sticky tofu, pickled tofu) and frozen tofu (thousand-layer tofu, kori tofu). Tofu byproducts are also very popular, and this includes tofu skin (yuba) and soy pulp (okara).