Rigatoni is a type of tube-shaped, medium-sized pasta with ridges running lengthwise down the outside of the tube. Unlike penne, which can be ridged or smooth, rigatoni has straight-cut ends, and it's larger.
Rigatoni originated in Italy, and is especially associated with Rome and central-southern Italy. Its name comes from the Italian word rigato, which means "ridged" or "lined." The ridges on the outside and the wideness of the tubes help catch and hold onto chunky sauces like Bolognese, or the eggplant, tomato, and salted ricotta sauce of the Sicilian dish called pasta alla Norma. While rigatoni is similar in size to ziti, the latter is usually smooth on the outside and narrower in the middle.