What is the rule for Jewish people relating to meat and dairy? and why?

Many Jews follow the laws of kashrut; the dietary laws set down in the Torah (the first five books of the Bible). The first step in observing the laws of kashrut is to determine whether the ingredients in the food to be eaten are in fact kosher (the Jewish laws regarding food preparation)

For the devout Jew all of life is dedicated to God and there are a strict set of rules to follow. This is true for food, Jews are allowed to eat certain foods known as kosher. Forbidden foods are known as treyfah.

These are the animals which you are permitted to eat ... anything which has a completely split hoof and chews the cud, this you may eat ... (Leviticus 11:2-3)

All plants are kosher, but not all animals, birds or fish. Animals must not only fit the criteria in Leviticus but must also be killed in a special manner and have all the blood removed before the meat can be eaten by Jews.

After limiting the types of animals that may be eaten, the laws of kashrut dictate how they must be killed and prepared - Jews may only eat animals and birds that have been killed by Shechitah. Shechitah is killing the animals by slitting the throat with a very shape knife. This has been shown to be painless to the animals, as causing pain to living things is against Jewish law. The theory is that the shape knife cuts the carotid so that the animal loses consciousness before they are able to feel pain. By the time it is possible for the animal to feel pain it is already dead.

The third set of rules determine what foods may be eaten together. The rabbis divide all foods into three categories: milk, meat, and pareve. Pareve foods include vegetables, fruits, fish, and eggs, and may be eaten with any other foods. The meat category includes any poultry or land animals. All dairy products, such as cheese and yogurt, are included under milk. According to the prohibition 'You shall not boil a kid in its mother's milk', milk and meat may not be eaten together. To prevent any possible mixing of the two, separate dishes for preparing and serving them are necessary. If a dish is used for both, it is non-kosher and must be koshered, usually by immersion in boiling water. Before then, anything prepared or served in it is non-kosher. There is also a waiting period after eating meat before milk may be eaten. This varies according to different traditions, but is generally three to six hours. There is no waiting period after eating milk products, as long as the mouth is rinsed out between the two with a pareve drink.

There is a theory that kashrut was actually designed to keep the Israelites healthy. There is some merit in this idea; the inspection of animals, the exclusion of fatty animals such as pigs, and other laws are often suggested today by health experts. However, some of the rules seem pointless, such as the separate dishes. It seems likely that these laws were included to keep Jewish people united. Jews around the world follow the exact same dietary restrictions, and that is one of the factors that has kept the religion strong throughout its history.

Torah says that you cannot boil a kid in it's mother's milk. In the beginning, this was to mean that you could not heat up red meat and milk in the same pot. While in exile it became rabbinic law to keep all meat and dairy separate. This was intended to keep an observant jew from accidentally breaking a mitzvot (commandment).

No meat and dairy on the same plate. Most orthodox or conservative jews keep separate china for meat and for dairy. It has to do with the "milk of the mother and blood of the calf." Although, I'm not sure of the exact Levitical reference. So, you'll never see a Hasidic Jew, for instance, eating a cheeseburger.

They are not supposed to mix the old with the young. Milk products cannot be prepared in the same dish as meat products. Even if separate servings, they should not be on the same plate. So meat and cheese lasagna is a no-no and a cheeseburger is a no-no. If they eat a steak with a side of broccoli cheese casserole, the side has to be served on a separate plate. And as always, the food must be kosher.

In general, Jews do not eat meat and milk products together. This stems from verses in both Exodus and Deuteronomy (Ex. 23:19; Ex. 34:26; Deut. 14:21) forbidding the boiling or "seething" of a kid (as in young goat) in its mother's milk. Rabbinical tradition eventually expanded this to all meat/milk combinations being forbidden. This is primarily a tradition of Ashkenazi Jews (those from eastern Europe); Sephardic Jews (those tracing their ancestry to western Europe and Spain in particular) do not generally consider the consumption of milk with the meat of birds to be forbidden, since of course a bird does not produce milk.

They cannot be mixed. The reason is the repeated injunction in the Torah against boiling a kid in its mother's milk. From the wording and unusual repetition we derive the law that milk and meat may not be mixed.

There is more information here:

http://www.jewfaq.org/kashrut.htm

In short: Can't eat it together. Cause god said so.

Check this link: http://en.wikipedia.org/wiki/Kashrut for more info on the jewish dietary laws.

Many people think its hygiene reasons. But its not, its just because god said you can't cook a child in its mothers milk. Today that includes all meat, not just mammals.

all of them provide a different mixture of nutrients and that is why a variety of both strongly recommended by nutritionists and dietitians.

"And the swine, because it divideth the hoof, yet cheweth not the cud, it is unclean unto you: ye shall not eat of their flesh, nor touch their dead carcass."

Deuteronomy 14:8

Jews follow the Old Testament Teachings

The basic rule says

"And every beast that parts the hoof, and separates the cleft into two claws, and chews the cud among the beasts, that you shall eat."

This is from the King James version, but they are all basically the same.

They're allowed to eat pork chops only if it is half price