Tofu is soybean curd, which is made by coagulating tonyu (soy drink). Nigari (magnesium chloride) is commonly used to make tofu in Japan. Tofu is rich in protein.
Kinugoshi-dofu (silken tofu) is the softest tofu. It has very smooth texture. Momen-dofu (cotton tofu) is made by draining some moisture, so it is firmer than kinugoshi-dofu.
Tofu don't stay fresh so long. Be sure to refrigerate it in fresh water and eat within one or two days.