The laws of Kashruth define what is and is not Kosher
The word Kosher comes from the hebrew root כשר which means fitting or appropriate. Food which is fitting or appropriate for a Jew to eat as defined by the laws of Kashruth(from the same root) is therefore termed "Kosher". The laws of Kashruth are the oral laws that the Rabbis set down based on the written laws specified in the Torah regarding that food which a Jew is permitted to eat1.

A few general notes (in no particular order)

  1. While most animals must be killed (schechted) in accordance with Jewish law, (with perfectly sharp knives, covering the blood of wild animals etc.) Fish are considered prepared and ready to eat simply by being caught. Which is why kosher sushi can be prepared.
  2. The gid haNasheh, the sciatic nerve, must be removed, Jews are forebidden to eat it directly in the text of the Torah itself. (bereishith/genesis 32:33 Yaakov/Jacob was wounded in the sciatic nerve in his fight with the angel.)
  3. The subtleties of the laws of Kashruth differ greatly among different religious Jewish traditions. (Sephardi and Ashkenaz for example)
  4. There are some very specific insects which we are permitted to eat. There is much halachic discussion as to which insects these are as well as when we are permitted to eat them.
  5. Lastly, in the absence of all Kosher food, a Jew is permitted to eat non-Kosher food for survival purposes, but only in extremis. In other words if a Jew ended up on a desert island with no edible source of food except wild pigs, s/he would be permitted to eat them. Still they would be required to kill it first due to the restrictions of not eating of a living animal. (eyver min ha Hai) This is certainly not a loophole for people to live their entire lives eating non-kosher because they chose to live in a place with no easy access to kosher food. According to Jewish Law they would be required to move as soon as it is at all feasible.
  6. Also, there are many times throughout the year where Jews are required to eat or drink specific foods or types of foods.

An entirely separate time-bound category of kashruth

  1. During the holiday of Pesach/Passover which is seven days long, (eight outside of Israel) all leavened bread is prohibitted. Leavened bread is defined as any flour of any or all of the five grains (wheat, barley, spelt, oats, rye) mixed with water that has had enough time to rise (usually 18 minutes) before it has been fully baked.
  2. While all vegetables and fruit are permitted, one may not eat from the fruit of a tree in the first three years of its fruit production.
  3. It is forebidden to eat any fruit or vegetable that was planted or harvested in the land of Israel during any seventh year of the Shmita cycle.
  4. There are certain fast days upon which all food is forbidden. (People who are sick or pregnant are an exception.) They are, Yom Kippur (10th of Tishrei), Tisha B'av (9th of Av), Asarah B'Tevet (10th of Teveth) and Shiva Asar B'Tamuz (17th of Tamuz). There are other fast days but these are the big four.
  5. There is an accepted Jewish custom not to eat meat for the three weeks leading up to the fast day of Tisha B'av.


More complex special-case subtleties of Kosher Law

  1. In the time of the Temple, it is forbidden to eat of any produce prior to the taking of the holy tithe.
  2. According to the Rambam/Maimonides in the midst of a war a soldier is not liable for eating non-kosher food found in an enemy camp; even if they have a ready supply of kosher food. This is a very extreme case (from what I have heard it is) meant to illustrate that during warfare one cannot expect soldiers to exercise total control over themselves.
  3. A Jew cannot eat food cooked (by or for a Jew) on shabbath/Saturday, while they can eat food on a holiday prepared specifically for that holiday. (In addition to food prepared during the week of course.)

while this writeup is meant to cover (in a general way) most of that which was left out in early writeups, it is in no way exhaustive. There is far far far more to be said on the halacha, the Jewish law, of preparing and eating food. Please inform me if I have left out anything drastic or if I have misconstrued or simply erred regarding Halacha. As always, when in doubt consult your Rabbi.
1. This intro was added at Gritchka's suggestion. It is redundant for clarification purposes. As someone who is unfond of redundancy, I apologize.

כשר

Kosher is a Hebrew word meaning “allowed” or “proper”. In Jewish law it refers to foods that Jews are allowed to eat and food-related practices they must follow. It has also been a prominent word in Jewish slang for quite some time, used to indicate legitimacy in any field. “It wouldn’t be kosher” is the Jewish equivalent of "shady", "improper", "undesirable" and “not quite cricket”, and “kosher” has become an all-purpose endorsement that can indicate any kind of quality, legality, or appropriateness. In the last generation or so, this usage of the word has become common amongst non-Jews as well.

The slang usage has spread so far in recent times that it has widely eclipsed the technical usage, and many people who now use the word have only a vague idea what it actually means in Jewish law. Most people understand that pork is not kosher, and that kosher meat has been slaughtered by certain methods to guarantee the meat’s purity and a humane death for the animal in question. But these simple rules are only the tip of the iceberg, and the regulations of kashrut influence nearly every aspect of observant Jews’ lives.

Many of these regulations come from the Bible itself, mostly in Leviticus 11 and Deuteronomy 14. Others have been added or clarified in the Talmud and other additions to Jewish observance.

    A LEXICON
  • Kosher – “allowed”. Adjective for foods that Jews are allowed to eat. Hebrew pronunciation is ka-SHER, but anyone who did not grow up with Hebrew as a first language says KO-sher.
  • Kashrut – the body of laws and practices governing food.
  • Glatt Kosher – “smooth kosher” – a strict level of observance governing red meat.
  • Shechitah – literally “slaughtering”, this Hebrew word is used to indicate the proper kosher method of slaughter. From the same root we get the word shochet , the specific term for a kosher butcher.
  • Fleishig – Yiddish term for foods that have meat in them. Hebrew equivalent is basari .
  • Milchig – Yiddish term for foods that have milk in them. Hebrew equivalent is chalavi .
  • Pareve – Yiddish term for foods that are neither dairy nor meat, such as vegetables, eggs and gelatin. May also be written parve . However it’s written, it’s pronounced PAR-veh, not pa-REV or PARV.
  • Treyf – literally “torn”, referring to an animal which has been torn by a predator. Such animals are forbidden, so treyf has become the term widely used for all unkosher things.
  • Triple Treyf – joke term for things that are far beyond the pale. A bacon cheeseburger with Jell-O for dessert would be triple treyf. In actual practice, the term is meaningless. Treyf is treyf.
  • Nevelah – literally “carrion”. In addition to actual carrion, which is forbidden, this refers to parts of the body which may not be eaten.
  • Chametz – “leavened”. Refers to leavened bread during Passover. Forbidden, of course.
  • Halal – the Muslim equivalent of kosher. The code itself is very similar.



A FIELD GUIDE TO KOSHER ANIMALS

It will come as no surprise to anyone who has really read the Tanakh that many, many, many kinds of animals are forbidden to Jews. Most followers of the New Testament remember only Ten Commandments that they are supposed to follow, plus "turn the other cheek". Jews, on the other hand, have 613 – count’em, six hundred and thirteen – commandments. 613 is a number that comes up over and over in Jewish lore, much like the mystical number 216 in the movie Pi, so it’s fairly easy to remember the number. Remembering the commandments themselves is not quite so easy. Nor is it easy to keep track of the foods that are allowed, and it takes some practice before you start remembering even the general principles, but here’s a brief description of the animal kingdom as seen by the Jewish sages:

Fish – if it lives in the water and has fins and scales, it’s kosher. Fish are an interesting group because they are not considered meat, making them exempt from the rules on kosher slaughtering, and they can be eaten with dairy foods. Don’t worry, I’ll explain that in a minute.

Insects – the “winged swarming things” are all treyf according to modern interpretation. Leviticus 11:22 mentions some flying insects that are permitted, but nobody knows what species those Biblical Hebrew names refer to. It’s very likely that they are locusts, but we don’t know for sure, so just to be on the safe side all insects are forbidden.

Birds – birds were formerly considered all good except for a small group of species named in the Bible, mostly scavengers and birds of prey. This was obviously too good to last, so some smart-aleck pointed out that we don’t actually know all those Biblical species and some of them might not be scavengers after all. So the current ruling is that birds are not safe to eat unless they are a species that has always been thought of as kosher (chickens, geese, etc.). Pheasants, quails and the like are now treyf. Penguins are right out.

MammalsLeviticus 11:3 and Deuteronomy 14:6 refer to “beasts of the earth”, which is generally assumed to mean mammals. All mammals that have cloven hooves and chew their cud – ruminants, in other words – are kosher, with the exception of the camel and the pig, which are specifically denoted as off limits. So cows, sheep, goats and deer are all kosher, while hares, pigs both short and long, horses, hedgehogs, dogs, and in fact most of the mammals, are treyf.

All other living creatures are treyf, as well. This category includes all things that creep and crawl, such as reptiles, amphibians, rodents, Great Auks, arthropods that are not winged swarming things, platypuses, shellfish, dragons – and everything else you smartasses can think of. If it ain’t in the short list above, it ain’t kosher.

(In case of complete memory failure, you might want to skip the animals altogether and just eat a pomegranate. You’ll remember pomegranates because they have 613 seeds each. Uncanny, isn’t it?)

VEGANS DON’T GET NO FREE RIDE:
KOSHER PLANTS

For general consumption, the laws of kashrut concerning plants are very simple: all plants are kosher, and only need to be cleaned and inspected to make sure there are no insects hiding amongst the leaves.

Farmers, on the other hand, work under an arcane set of tithes and donations, most of which are only ritually carried out. Ten percent of every harvest is meant to be tithed, but since there is no Temple in Jerusalem and the cohanim have been considered impure and unfit to receive tithes for at least a millennium, the “tithe” consists mostly of a symbolic separation of the cohanim’s portion – no crops are actually taken away. There are a total of five different tithes and charity donations which need to be reenacted – some every year, and some only in certain years of the seven-year crop cycle.1

Fruit trees must not be harvested at all in their first three years, or in the first three years after transplanting. Fruits borne in these years are called orla and are discarded. In Israel, the fruits of four-year-old trees must not be harvested either, as they are supposed to be eaten only in Jerusalem. This may sound bizarre, but what the hell – there had to be some kind of compensation for those who choose to live in the most hotly contested city on the planet.

Finally, all trees and other perennial crops must be allowed to “rest” or for one year in every seven. No trees can be planted or harvested during this year. This practice is called shmitah, Hebrew for “casting aside”.

THE BLOOD IS THE LIFE:
KOSHER BUTCHERING

Shechitah, the kosher method of slaughtering, is a critical aspect of kashrut. It must be done without causing the animal undue suffering, and in such a way that removes the majority of the blood, which is forbidden, and insures the cleanliness of the meat. It is to be done quickly and cleanly, and with a mind towards respect for God and his creation – there is even a blessing that accompanies the act. A kosher butcher or shochet, being personally responsible for the life and death of numerous animals and the spiritual well-being of every Jew in his area, is not just a big guy with a cleaver but a man well-versed in all aspects of Judaism, especially the laws of kashrut. He is almost as important to a Jewish community as the rabbi – and in many small communities throughout history, he was the rabbi.

A shochet’s first task is selecting animals to be slaughtered. Only healthy mammals and birds are kosher. (Fish, for various reasons, are exempt from almost all of the regular laws.) Animals that show any signs of sickness are strictly forbidden, so the shochet has to inspect every animal. This selection process is part of what makes kosher meat so famous for its healthiness. Roadkill, by the way, is not kosher, nor is any animal that dies of natural causes.

When an animal has been approved and the shochet has recited the appropriate bracha, there is only one acceptable way to kill it, and that is with one sudden and forceful cut to the throat with a very sharp knife, severing the jugular vein and causing massive blood loss that kills the animal instantly. Due to the rapid loss of blood pressure in the brain, the brain should immediately stop functioning even if the animal does not die on the spot, so that it is almost unaware of its impending death. Even in the worst cases, death should not take more than a few seconds. This is widely considered the most humane way to slaughter an animal, and kosher slaughtering is actually cited as one of the two acceptable methods in US law2.

The blood must be drained immediately. The organs are then removed from the carcass, and inspected for flaws and health problems that would render the animal unfit for eating. In addition to the organs that any butcher would remove, this includes the sciatic nerve, which is specifically forbidden. (Since it is difficult to remove, the entire hindquarters of the carcass are often sold to non-Jewish butchers.) Certain fatty tissues known as chelev are also prohibited, and these are trimmed away and destroyed.

(At this time, the lungs may also be inspected for perforations and adhesions. If there are none, the meat can be certified “glatt kosher”, from the Yiddish for “smooth”. Some Jews will not eat red meat that is not certified glatt kosher, but this is an ultra-strict interpretation which many Jews consider superfluous.)

One especially important aspect of kosher slaughtering is the removal of all blood from the animal. According to Judaism, the life of an animal is contained in the blood, and is therefore forbidden. All blood must be drained immediately from slaughtered mammals and birds. (Fish blood is exempt). Kosher slaughter removes most of the blood by draining. The remainder must be removed by broiling or salting within 72 hours of slaughter. All of the blood is then buried with rituals. Remember “the blood is the life”? It’s not just a catchphrase.

Also note that eggs with blood spots in them are unclean. For this reason, it is recommended to break eggs into a disposable container, not directly into a cooking pan. You’ll see why in just a minute.

THE FOUR - NO, THREE! - FOOD GROUPS:
DAIRY, MEAT AND PAREVE

The Bible forbids boiling a kid in its mother’s milk. (That’s a goat kid, not a human kid, which wouldn’t be kosher anyway, you heathens!) This rule, which is repeated three times in the Bible, has long been interpreted as a commandment not to mix meat with dairy foods. A kosher meal is usually designated as a meat meal or a dairy meal. A third class of foods, known as pareve , consists of all things that are neither meat nor dairy, and may be eaten with meat or dairy. Pareve includes all plant matter, along with things like salt (see below), cola, and oddities like gelatin and glue.

Once you have eaten meat, you must wait “a significant amount of time” before eating or drinking dairy. Three hours is the standard waiting period, but some Jews wait up to six hours. This is the reason for the tremendous popularity of non-dairy coffee creamer in Israel. However, dairy can be followed with meat almost immediately, provided you wash your mouth out first and eat a neutral food to eliminate the dairy “essence” from your mouth.

Up to this point the commandments were pretty straightforward, right? Well, this is where the headaches start. Not only are there dairy and meat foods, but dairy and meat utensils as well. Kitchen utensils pick up the meat or dairy nature, so to speak, in the presence of heat, so any pan that you have cooked a hamburger in becomes a “meat pan”. A plate which has held macaroni and cheese becomes a dairy plate, etc. Keeping kosher means at least two complete sets of dishes, one for meat and one for dairy, which must never even touch each other.

(Remember the egg with the blood spots? The taint of blood can transfer to a hot pan just like the meat nature does. A mixing bowl that accidentally catches a bloody egg will remain kosher if it is promptly washed – these things only transfer in the presence of heat – but most kosher cooks will try to avoid that sort of thing as well.)

Like utensils, the kitchen’s work surfaces can acquire a food’s nature if any heat is applied to them. Stove tops and sinks become meat or dairy surfaces if any food is dripped on them. Trivets, spoon rests, mixing bowls and dishpans become tremendously important in this context. Dishwashers are a problematic and much debated area, and are often not used at all in kosher homes, or used only for meat dishes. The kitchens in kosher restaurants and the IDF are routinely twice as big as non-kosher kitchens, because they have to have two of every single item.

It should be obvious that keeping two sets of dishes which have to be separated at all times is a big commitment, and is much more difficult than simply remembering which animals are kosher and which aren’t. But wait, we’re not done yet....

FOR SALE, TWO SETS SERVICE FOR FIVE
TO BE REPURCHASED IN EIGHT DAYS
(MUST NOT BE USED)

Did I say two sets of dishes? Make that four, because an observant Jewish family also needs two more sets for Passover. You see, during Passover the house and all its contents must be ritually cleansed and searched for chametz . Chametz means leavened bread. In remembrance of the Exodus and the sacrifices the Jews made in Egypt and during their escape to the Promised Land, modern Jews are forbidden to eat anything with leavening in it during the days of Passover.

Anything that is made of wheat, rye, barley, oats or spelt and cooked for longer than eighteen minutes is chametz . All bread and almost all grain products are chametz . And, of course, dishes and utensils that have come in regular contact with chametz are chametz as well. They all have to be discarded or sold to non-Jews before Passover begins.

You can’t just rummage through your cupboards for bread and crackers and hope for the best, either. The entire house has to be cleaned from top to bottom, so that not a crumb of chametz remains hidden amongst the dust bunnies in Moishe’s room. We’re talking on-your-knees-with-a-toothbrush cleaning here, a level similar to the standards of CDC lab inspectors and drill sergeants in elite military academies. Every bit of chametz , along with all dishes and utensils, must be sold to gentiles or discarded. In the Interweb age, there are actually websites that facilitate the sale of chametz dishes to helpful non-Jews. These sales are, of course, meant to be temporary, but they are real sales for all that, and are legally binding.

The alternative to discarding the chametz dishes is a lengthy process of cleaning and ritual purification, supervised by rabbinical workers. Commonly called “kashering”, this mammoth undertaking is impractical for most Jewish families, and is routinely practiced only in restaurants and IDF kitchens.

REGULATING KASHRUT

In a perfect world, kashrut would not have to be regulated. There are no blessings that need to be said to make something kosher, no special purification processes or anything else that ought to require rabbinical intervention. In the days when the foods we eat were a little more natural and locally produced, there was very little need for kosher certification. If you ever encountered a food that you weren’t sure about, you went and asked your rabbi.

In the modern world this is no longer feasible. There aren’t enough rabbis with degrees in bioengineering and organic chemistry. Labels are no help, either. The words “natural flavorings” can mask all sorts of shady ingredients, and very few people actually know where things like tripotassium phosphate come from. In fact, I still don’t know where tripotassium phosphate comes from, but I do know that it’s kosher. I know this because in our cupboard there is a box of Cheerios, which has the stuff in it, and on that box is a little “U in a circle” symbol.

This U is the seal of the Union of Orthodox Jewish Congregations, the most widely recognised symbol of kosher certification. It is a registered trademark, and in order to display it on a Cheerios box, General Mills’ facilities and manufacturing processes have to have been inspected by the Orthodox Union’s rabbinical workers for any kashrut violations. Every year these inspectors check on Cheerios and thousands of other foods to make sure they are completely kosher. With their seal of approval on my Cheerios box, there is no doubt in my mind that tripotassium phosphate, whatever it is, is something that a Jew can safely eat.

There are several other groups that do kosher certification, each with their own seal of approval. There are also other symbols indicating meat/dairy/pareve status and whether the food is kosher for Passover. For a comprehensive guide to these certifications, see kosher symbols by edibleplastic.

The most important thing to remember, however, is that the letter K itself cannot be trademarked, and an unadorned K is often used by manufacturers who can’t be bothered to get certified or have been refused certification. Jell-O, for example, is not certified and is almost definitely not kosher, but it has a K on it. The Hebrew alphabet isn’t a trademark, either, so boxes bearing the word כשר may or may not be kosher (although I would guess that anyone who actually prints things in Hebrew on their labels has more than a passing interest in kashrut).

KOSHER WINES

m_turner has already written an excellent writeup on kosher wine, so I will not duplicate his efforts. For those who lack the patience to follow that link, I will say only that because many wines were once made for pagan rituals and consecrated to foreign gods, Jews are not allowed to drink any wine that has been handled by a non-Jew. If a gentile so much as touches the label of a kosher wine, the wine is no longer kosher.

This does not apply to boiled wines, which is why most widely distributed kosher wine used to be boiled (and terrible). It does apply to grape juice, and thereby creates another problematic area, because many blended juices today contain grape juice. These are universally off limits, even if they claim to be kosher.

A STICKY ISSUE:
KOSHER GLUE AND OTHER ODDMENTS

The laws of kashrut do not apply only to actual foods, but to anything that can be ingested. For this reason, Israeli postal stamps use a glue that is certified kosher. (Glue comes from collagen, which is found in the connective tissues of animals - see gelatin for more on that topic).

Kosher salt is another thing that makes most non-Jews scratch their heads. What on Earth could make salt unclean? The answer is probably not what you expect.3 In fact, the only difference between kosher salt as a varietal name and “regular” salt is that regular salt routinely contains additives and kosher salt does not. Furthermore, most salt is ground down to a tiny particle size, while kosher salt comes in larger crystals. But grinding salt crystals does not make a salt kosher, and kosher salt can have additives in it. The real reason this stuff is called kosher salt is that this kind of salt is used to salt kosher meat after shechitah. Its large crystals make it much more absorbent than most other salts, so it removes blood more efficiently.

Observant Jews should also note that the word “kosher” is not copyrighted or otherwise controlled, so not everything that says Kosher Salt on the box is certified kosher.

HALAL

Islam and Judaism are more closely linked than most people like to admit, and halal food is almost always technically kosher – that is, it comes from animals that Jews are allowed to eat and is slaughtered in a humane manner very similar to shechitah. For obvious reasons, halal food lacks kosher certification and has been overseen by followers of the “wrong” religion, but the codes themselves are very similar. Furthermore, both religions specifically state that should a believer be forced to eat unclean foods through unpreventable circumstances he is absolved, but that one should do one’s best to comply with the laws.

In practical terms, this means that if a strict Muslim is stuck in a strange country without a source of certified halal food, his safest alternative is a kosher butcher, and vice versa for observant Jews. Kosher certifications on packaged foods are also reliable indicators of foods that are safe for Muslims to eat. These may sound like facetious suggestions to many people, but I can assure you that people do these things all the time.

LEVELS OF OBSERVANCE

Not all Jews keep kosher the same way. I have spoken of generic “observant Jews” and “kosher kitchens” only for the purpose of listing the rules as they are written or interpreted by the sages. In fact, relatively few Jews follow all of these rules outside of Israel and a few distinct Jewish communities. The actual practices of kashrut vary widely, and even Jews who consider themselves observant commonly disagree on which rules are the really important ones. There are, for example, many small differences between the Sephardic and Ashkenazi traditions of kashrut, and vast differences between Orthodox, Traditional and Reform observances. Not for nothing do we say that where there are two Jews, there are three opinions.

Some Jews totally ignore the subject, as they did on the kibbutz where I grew up (kibbutzim tend to be staunchly unreligious places, where “traditional food” means burekas and cheap wine on Fridays and barbecues by the Sea of Galilee for Yom Kippur). Some Jews refrain from eating pork and other treyf animals, but see nothing wrong with a cheeseburger from McDonald’s. They may not eat bread during Passover, but they don’t dispose of the chametz altogether – they just pack it into a “chametz box” and store it in the closet for a week – and they don’t have special Passover dishes. This is probably the most common level of observance worldwide. Others obey the letter and the spirit of every rule, down to the point of refusing to buy even Israeli wine from Christian winesellers, selling their chametz utensils to non-Jews during Passover and buying them back after the holiday, and having their dairy spoons kashered if they are accidentally used for chicken soup.

My mother, who converted to Judaism in her late teens, went through several different levels of kashrut observance before settling on her own compromise. She rigorously separates meat and dairy, and never ate pork even before we moved to Israel (you can find pork in Israel, but it’s not easy – Jews and Muslims alike can lose their respective certifications for handling it, and those certifications are too important for most merchants to risk). On the other hand, she sees nothing wrong with having milk in her coffee shortly after a meat dinner, and I’m almost sure she sneaks in a shellfish dinner every once in a while. It annoys her when I mix up the dairy and meat dishes, but she doesn’t run to the rabbi to have them kashered afterwards. Her particular priorities are not typical, but the fact that she picked her own way to keep kosher is absolutely typical.

SO WHAT’S THE POINT?

Excellent question, Grasshopper. What, indeed, is the point of all this? Countless generations of Jews have kept kosher simply because they believe God told them to, and I guess that’s a good enough reason if you believe in it. But surely God wouldn’t give his Chosen People so many rules to follow without rhyme or reason, would he?

In the late Twentieth Century, it became fashionable amongst Jews and gentiles alike to view kosher food as being more healthy than non-kosher. For many aspects of kashrut, this is true. Shechitah is not only more humane than other methods of annihilation, but also guarantees a certain level of sterility, and the separation of meat and dairy has probably prevented at least a few cases of cross-contamination. Prohibiting the consumption of roadkill and cows that died of mad cow disease turns out, surprise surprise, to be a rather sensible policy. The chelev fatty tissues that are removed during shechitah have been found to be quite different in composition from the fatty tissues immediately surrounding them. And many of the treyf animals have been known since medieval times to be somewhat less healthful than the kosher species.

Still, this doesn’t explain why we should wait three hours for a drink of milk after our mad cow burger, nor does it justify buying four complete sets of dishes when one or two should be more than enough. No one has ever discovered a convincing reason for the prohibition of rabbit meat, either. What reason, if any, can there be for those rules?

Notwithstanding the health angle and the fairly significant point that the Creator of the Universe allegedly ordained these practices, the most important reason for keeping kosher is a spiritual one. It is a constant reminder of one’s faith, meant to insure that the practising Jew is mindful of the mitzvot at all times. Like regular prayers and Catholic confessions, it fosters awareness of the religion. An observant Jew does not simply forage. He can’t shop or cook or eat without at least a passing thought for God’s commandments. He has to pay attention. In doing so, he is reminded of the fact that he is a Jew and has other commandments to follow. Hopefully this helps to keep him on the straight and narrow path.

I should also point out two other non-religious justifications for kashrut. First of all, thinking about what you eat is a good, common sense idea. It can help you enjoy your food more fully, and helps you avoid unhealthy foods and impulse eating. This is not to say that Jews don’t snack or overeat – the word nosh is Yiddish, after all – but it does keep them from simply stuffing their mouths with any edible thing they can find. (As an added perk, it has helped protect Jewish kids from some of the absolute worst food-like items humanity has invented, as the most sickeningly artificial “snack cakes” and cookies are usually not certified kosher.)

And as you may have guessed, it is incredibly hard to keep kosher outside of the Jewish community. Non-Jewish restaurants serve dairy and meat on the same plates as a matter of course. Meat is not slaughtered according to kosher rules, nor is it inspected for the imperfections that can make it treyf. Prepackaged foods are made out of forbidden animals and with a hodge-podge of meat and dairy elements. Gentile winesellers unkosher the wine with their very touch, and even your non-Jewish friends have so much trouble inviting you over for dinner that they probably won’t try it more than once.

Although they may seem like unnecessary hardships or isolationism for its own sake, these difficulties actually help to unite the Jewish community in exile. Jews have to stick together if they want to follow the mitzvot. They have to shop in Jewish shops and have Jewish friends. For a people that has spent most of its history living amongst Christians and Muslims, this cultural integrity is highly important. Thanks to traditional practices like kashrut, the Jews have been able to maintain a distinct identity that has changed very little in thousands of years, even as they settled in dozens of countries and adopted new customs, languages and foods in every one. Without these practices, it is entirely possible that the Jewish people would have been assimilated beyond recognition long ago.

And that, dear chaverim, just wouldn’t be kosher.


  1. Rabbi Moshe Heinemann, Terumos and Ma’asros, The Star-K Online:
    http://www.star-k.com/kashrus/kk-medi-terumos.htm
  2. US Code, Title 7, Chapter 48, Subchapter 1902:
    http://assembler.law.cornell.edu/uscode/html/uscode07/usc_sec_07_00001902----000-.html
  3. (It’s also not what I thought before researching this writeup. A few months ago, I had a lengthy catbox discussion on the subject of kosher salt. In this lecture I explained with great conviction that kosher salt had to be rock salt. I must apologize to those who were misled through my tenuous grasp on reality.)

Ko"sher (?), a. [heb. kosher fit, proper.]

Ceremonially clean, according to Jewish law; -- applied to food, esp. to meat of animals slaughtered according to the requirements of Jewish law. Opposed to tref. Hence, designating a shop, store, house, etc., where such food is sold or used.

 

© Webster 1913.

Ko"sher, n.

Kosher food; also, a kosher shop.

 

© Webster 1913.

Ko"sher, v. t. [imp. & p. p. Koshered (?); p. pr. & vb. n. Koshering.]

To prepare in conformity with the requirements of the Jewish law, as meat.

 

© Webster 1913.

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