Soba (そば) is a type of Japanese noodle. It is most often served in noodle soups or plain with vegetables and meats.
Soba is made with buckwheat flower. Soba literally means “buckwheat” so it is possible that when the Japanese speak the word they are referring to a different food, but since soba is so common in Japan is it highly unlikely any Japanese individual will refer to buckwheat without clarifying they are not speaking of the noodle. It is thinner than Udon, another popular noodle type of Japan, and many people refer to any thin noodle as Soba in order to distinguish it from Udon, even though this is not entirely accurate.
Buckwheat was introduced to Japan during the Nara period (710-794 AD). Buckwheat flour was not used for noodles, however, until the 1700s. The barley used to make buckwheat flour was used until that point in soups at tea ceremonies. During the Edo period, Soba was the noodle of choice over Udon because of a variety of problems that were occurring in the rice and wheat that they were culling. Today, soba is still more traditional in Tokyo, though most restaurants offer both Soba and Udon as a choice.
Soba may be served cold, on a plate, with a sauce to dip it in. It is not uncommon to see Soba in soup. It is also not uncommon to have soba served on a plate with vegetables and spices on top, making it resemble the Italian style of serving noodles, though it is still eaten with chopsticks.
These days, with the introduction of other cultures into Japanese food choices, soba may be served in any form and is often used to create new food dishes that are not based on tradition.