Biscotti means "twice cooked" in Italian (biscotto in its singular form). Traditionally, biscotti are made by baking cookie dough in long slabs, cutting these into slices, and baked once more to dry them out. Because they are low moisture cookies they are able to be stored for long periods of time. In Italy, biscotti are often served with wine, such as vin cotto. In the U.S. they are often served with coffee. A true biscotto should be hard and crisp, not soft and cakey.
There are many variations, but here are some recommendations: 1 t. orange extract, zest of 1 orange with 1-½ c. pistachio nuts. Can also use pine nuts or hazelnuts in place of almonds. Also delicious half-dipped in chocolate.