Pasta (Italian pasta, from Latin pasta "dough, pastry cake", from Greek past? (pasta) "barley porridge") is a generic term for foods made from an unleavened dough of flour and water, and sometimes a combination of egg and flour. Pastas include noodles in various lengths, widths and shapes, and varieties that are filled with other ingredients like ravioli and tortellini. The word pasta is also used to refer to dishes in which pasta products are a primary ingredient. It is usually served with sauce. There are approximately 600 different shapes of pasta. Examples include spaghetti (thin rods), maccheroni (tubes or cylinders), fusilli (swirls), and lasagne (sheets). Two other noodles, gnocchi and spÃ¤tzle, are sometimes considered pasta. They are both traditional in parts of Italy. Pasta is categorized in two basic styles: dried and fresh. Dried pasta made without eggs can be stored for up to two years under ideal conditions, while fresh pasta will keep for a couple of days in the refrigerator. Pasta is generally cooked by boiling. Wheat (Triticum spp.) is a worldwide cultivated grass from the Fertile Crescent region of the Near East. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize (784 million tons) and rice (651 million tons). Wheat grain is a staple food used to make flour for leavened, flat and steamed breads, biscuits, cookies, cakes, breakfast cereal, pasta, noodles, couscous  and for fermentation to make beer, alcohol, vodka, or biofuel. Wheat is planted to a limited extent as a forage crop for livestock, and the straw can be used as fodder for livestock or as a construction material for roofing thatch. Although wheat supplies much of the world's dietary protein and food supply, as many as one in every 100 to 200 people has Celiac disease, a condition which results from an immune system response to a protein found in wheat: gluten (based on figures for the United States).