The West has a single premier hard, durum-wheat noodle, but the Japanese capitalize on the grain's possibilities for variation.
Somen are thin, white stick noodles made of wheat flour, water, and oil, and are almost always eaten cold. They are commonly sold in packages of single servings bound by a ribbon.
Udon are square-edged, thick whole-wheat noodles usually served in soups and hot pots. When they are sold fresh, they are called noma udon.
Soba are beige stick noodles of buckwheat, excellent both hot and cold. They can generally be substituted in recipes calling for udon.
Ramen are fine, white wheat noodles, a pasta that cooks quickly in water or broth. They have become the ultimate fast food, sold all over the world in packages with soup flavoring.
Cooking: All these noodles in their dried form can be cooked like any pasta in boiling water. Very thin noodles, to be served in broth, can be quickly cooked. Somen take only 3 to 4 minutes; soba, 6 to 7 minutes; and the thickest, udon, 15 minutes or more. Of course, these times can vary according to the noodle, so always check for doneness after the first few minutes.