Although cooks in America tend to combine sauces with any variety of pasta that comes to mind, most Italians associate particular kinds of pasta with a region’s own specialties and sauces. In northern Italy, fresh pasta made with eggs is more popular than the dried pasta, often made only with water, usually served in the south. To delineate which sauces are traditionally served with what pasta would be the subject of an entire book, but there are a few principles and traditions that help make a judicious pairing of pasta and sauce.