Land animals must have cloven (split) hooves and must chew the cud, meaning that they must eat grass.
Seafood must have fins and scales. Eating shellfish is not allowed.
It is forbidden to eat birds of prey. Only clean birds, meaning birds that do not eat other animals, can be eaten. Poultry is allowed.
Meat and dairy cannot be eaten together, as it says in the Torah: do not boil a kid in its mother’s milk (Exodus 23:19). So Jews who follow these dietary rules cannot eat cheeseburgers for example. Often this rule is extended further, so that people wait up to six hours after eating meat before they eat dairy.
Food that is not allowed is called treif. Examples include shellfish, pork products and food that has not been slaughtered in the correct way, known as shechitah. Animals must have their throats cut with a sharp knife by a shochet, a person trained to slaughter animals in a kosher way. The blood must then be drained from the animal because in in the Book of Deuteronomy (12:23) it forbids Jews to eat or drink blood. No animals that have died naturally can be eaten.
Parev
Neutral foods, that can be eaten with either meat or dairy, are called parev and these include vegetables, pasta and rice. As long as these are washed thoroughly before eating, no kosher rules will be broken.