Traditional Jewish dietary laws are based on biblical legislation.
Only land animals that chew the cud and have split hooves (sheep, beef; not pigs, camels) are permitted and must be slaughtered in a special way. Further, meat products may not be eaten with milk products or immediately thereafter. Of sea creatures, only those (fish) having fins and scales are permitted. Fowl is considered a meat food and also has to be slaughtered in a special manner.