Kosher - Jewish Dietary Laws:

Kosher food is food prepared in accordance with Jewish Dietary Laws. The "kosherness" of a food is indicated by a symbol printed on the food package. Each symbol represents a particular agency's certification that the food has been processed in accordance with Jewish Dietary Laws.

In a nutshell, Jewish Dietary Laws say:

1. Certain animals may not be eaten at all.
2. Of the animals that may be eaten, the birds and mammals must be slaughtered in accordance with Jewish law.
3. Certain parts of permitted animals may not be eaten.
4. All blood must be drained from the meat or broiled out of it before it is eaten.
5. Meat cannot be eaten with dairy.
6. Eggs, fruits, vegetables and grains are considered pareve, and can be eaten with either meat or dairy.
7. Utensils that have come into contact with meat may not be used with dairy, and vice versa.
8. Grape products made by non-Jews may not be eaten.

Eating kosher foods is considered healthier as it is prepared with lots of guidance. Our sages also point out the various advantages of the kosher laws: the health benefits, the humane treatment of animals, their unifying effect on a dispersed people, and their role as shield against assimilation.

Nachmanides, the great 12th century sage and kabbalist, points out that "the birds and many of the mammals forbidden by the Torah are predators, while the permitted animals are not; we are instructed not to eat those animals, so that we should not absorb these qualities into ourselves." Kashrut can thus be seen as "spiritual nutrition": just as there are foods that are good for the body and foods that are harmful, there are foods that nourish the Jewish soul and foods that adversely affect it.