Tare refers to the packaging weight of a product. Another way of explaining tare weight, which is also called unladen weight, is by saying that it is the weight of an empty container. To get the real weight or net weight of a product, the tare weight of the container is (usually automatically) deducted from the weight that the scales show.
Tare weight is used regularly in the packing, as well, as transportation of goods. For example, salad greens placed in a plastic bag will have a tare weight of .01. This tare weight obviously does not refer to the weight of the salad greens being purchased, but that of the plastic bag. As seen in the previous example, even the tare weight of a plastic bag is computed when paying for a purchased product. The same is true for all products sold with tare weights of cans, glass jars, and any packaging used to determine net weights.
Tare weight is especially important in the transportation of goods since container vans–and the trucks and railway cars that carry them–are obviously very heavy. All their contents need to be unloaded in order to be weighed at borders and check-in stations. To avoid this hassle, containers and most trucks have their tare weight painted clearly on the outside or printed in marking plates. That way, the entire container/vehicles can instead be weighed along with the contents and just have the printed tare weight subtracted.