These are made from hard or soft wheat flour and water. If egg has been added, the noodles are usually labelled as egg noodles. They can be bought dried or fresh from Chinese markets, and many supermarkets and gourmet shops also stock both the dried variety and the fresh. Flat noodles are usually used in soups and rounded noodles are best for stir-frying or pan-frying. The fresh ones freeze nicely if they are well wrapped. Thaw them thoroughly before using.
Noodles are very good blanched and served with main dishes instead of plain rice. I think dried wheat or fresh egg noodles are best for this.