Passata is an uncooked tomato purée that has been strained of seeds and skins. It originated in Italy but is used throughout Europe.
 
Some people claim that passata can also be cooked, but most agree that it is uncooked. You will also see it spelled passato and passata di pomodoro, and it can also simply be called "strained tomatoes."
 
Tomato passata can be used in any recipe that calls for tomatoes where it is not important that there be pieces of tomato, such as sauce, soup, and stew. It's especially nice in dishes where you really want to a fresher tomato flavor to come through rather than a cooked down version