Kosher: What Can and Cannot Be Eaten?

The Torah gives very specific guidelines on which animals are permitted and which are forbidden. Here are the rules:

Land mammals. The only land mammals that are permitted are those that have cloven hooves (a divided hoof) and who also chew their cud. Cattle, sheep, goats, deer and bison are kosher food sources. Pigs, rabbits, squirrels, dogs, cats, bears and horses are prohibited food sources.
Sea life. Fish with fins and scales, such as tuna, salmon and herring may be eaten. Shellfish, such as lobsters, shrimp and clams are all forbidden. Also forbidden are eels, octopus, sharks, and whales.
Fowl. The Torah lists 24 families of non-kosher birds, including owls, eagles, falcons, gulls, hawks, ostriches and vultures. The Torah does not give specific guidelines on how to choose a kosher bird, but in practice, only familiarly used fowl, such as chicken, geese, ducks and turkeys are considered a kosher source of fowl meat.
Rodents and insects. All are prohibited. This rule leads to the practice of carefully cleaning and checking fresh fruits and vegetables for the presence of infestation before eating.
Any product derived from forbidden animals, such as their milk, eggs or fat, also may not be eaten. This rule is significant for industrial production of foods, which can be made non-kosher by certain ingredients, such as:

Rennet (an enzyme that comes from the lining of the stomach of certain animals). Rennet is used to make cheese.
Civet (a chemical secreted by the civet cat’s anal scent glands). Civet is a common additive found in frozen dairy desserts, baked goods, candies, puddings and gelatins.

All fresh fruits and vegetables are considered kosher.

Frozen or canned fruits and vegetables and those mixed with other items are non-kosher unless specifically certified as kosher.
Certain varieties of fruits, vegetables, and grains are prone to insect infestations and must be inspected and carefully washed before use to avoid eating forbidden insects.