Kosher food follows a set of dietary laws rooted in the Torah, the foundational text of Judaism. These laws govern which animals can be eaten, how they must be slaughtered, which parts of a meal can be combined, and even how produce is prepared. The system divides all food into three categories: meat, dairy, and pareve (neutral), each with its own rules.
Land Animals Need Two Traits
For a land animal to be kosher, it must meet both of two requirements: it chews its cud (meaning it regurgitates and re-chews vegetation as part of digestion) and it has completely split hooves. Cows, sheep, goats, and deer qualify on both counts. An animal that meets only one requirement is explicitly not kosher.
The Torah singles out four animals to illustrate the point. The camel, hare, and hyrax all chew their cud but lack split hooves. The pig has split hooves but does not chew its cud. This is why pork is the most widely recognized non-kosher food: the pig looks like it should qualify from the outside, but fails the internal test.
Fish Must Have Fins and Scales
Seafood rules are straightforward. A fish is kosher only if it has both fins and scales. Salmon, tuna, cod, and herring all qualify. Shellfish of any kind, including shrimp, lobster, crab, clams, and oysters, are not kosher. Neither are catfish, swordfish (whose scales are debated), sharks, or eels. Interestingly, every fish that has scales also has fins, so scales are the practical identifier. If you can see scales on a fish, it’s almost certainly kosher.
Birds Follow an Ancient List
Rather than giving physical characteristics, the Torah lists 24 species of birds that are forbidden, with all others considered kosher. The problem is that over thousands of years, the exact identity of some birds on that forbidden list has been lost. Jewish law addresses this through tradition: a bird is accepted as kosher only if there is a longstanding community practice of eating it.
Chicken has been eaten since the era of the Second Temple in Jerusalem. Goose and duck were likely consumed by Jews in Egypt before the Exodus. Pigeons, doves, and quail are confirmed kosher through biblical narratives. Turkey, though a New World bird, was widely accepted by Jewish communities after its discovery. Partridges and several songbirds also have centuries of documented use. Birds of prey and scavengers are universally recognized as forbidden.
How the Animal Is Slaughtered Matters
Even a kosher species becomes non-kosher if it isn’t slaughtered correctly. The process, called shechita, requires a trained practitioner who uses a razor-sharp knife with no nicks or imperfections in the blade. The practitioner constantly inspects the knife by running a fingernail along its edge, because even the tiniest nick can invalidate the slaughter. The cut must be swift and uninterrupted across the throat. An animal that died naturally, was killed by another animal, or was slaughtered incorrectly cannot be made kosher.
After slaughter, the animal is inspected internally. Certain defects in the lungs or organs can render an otherwise kosher animal unfit. The sciatic nerve and certain fats must also be removed, which is why kosher butchering is a specialized skill.
Meat and Dairy Cannot Mix
One of the most distinctive kosher rules is the complete separation of meat and dairy. They cannot be cooked together, eaten together, or even served at the same meal, regardless of whether they’re on separate plates. Observant households typically maintain two full sets of cookware, dishes, and utensils: one for meat meals and one for dairy meals.
Timing matters too. After eating meat, you wait six full hours before consuming any dairy. After eating dairy before a meat meal, the requirements are lighter: eat something neutral, rinse your mouth or take a drink, and wash your hands. Many people also wait 30 minutes to an hour after soft dairy. Hard aged cheeses, however, require the same six-hour wait before eating meat.
Pareve: The Neutral Category
Foods that are neither meat nor dairy fall into a third category called pareve. This includes eggs, fish, fruits, vegetables, grains, pasta, nuts, coffee, tea, and most snacks and soft drinks. Pareve foods can be eaten with either a meat or dairy meal, which makes them the most flexible category.
There are catches, though. A pareve food processed on equipment that also handles meat or dairy may lose its neutral status. Eggs must be checked for blood spots, which render them non-kosher. And certain fruits, vegetables, and grains need inspection for tiny insects and larvae, since consuming insects violates kosher law.
Produce Inspection for Insects
Insects are not kosher, and even a single bug in your salad is a problem. Leafy greens, broccoli, and berries are the highest-risk foods. Kosher practice calls for checking produce against a bright white surface under good light.
For leafy vegetables, the process starts with tapping the leaves against a white plate to dislodge any insects. If three or more bugs appear on the first check, that batch should be discarded entirely. If only one or two appear, a second round of tapping followed by a water soak can clean them. Leaves are soaked in a white container, removed one by one, and the water is inspected for at least a full minute.
Broccoli and raspberries are nearly impossible to fully clean once insects are found, because of all the tiny crevices where bugs hide. Strawberries are more manageable if the leafy stem is cut off first and the berries are washed and checked on a white surface. One technique involves chilling berries in the refrigerator, then placing them at room temperature on a white plate. Insects sense the temperature change and crawl out on their own.
Wine and Grape Products
Wine has its own layer of kosher law. Non-kosher wine isn’t just about ingredients. If wine is touched or moved by someone who isn’t Jewish during production, it becomes forbidden. This rule applies to grape juice and wine vinegar as well. For this reason, all wine requires kosher certification, with Jewish handlers overseeing every stage of production.
There’s an exception: wine that has been heated (called mevushal, meaning “cooked”) no longer becomes forbidden through handling. Most American kosher authorities consider wine mevushal once it reaches about 175°F, though some Israeli authorities require higher temperatures, up to 212°F. Mevushal wine is especially practical for restaurants and events where non-Jewish staff may pour or serve it.
Additional Passover Restrictions
During Passover, the eight-day spring holiday, kosher rules expand significantly. The central prohibition is chametz: any food made from wheat, rye, oats, barley, or spelt that has been allowed to ferment or rise. These are the same five grains used to make matzah (unleavened bread), but matzah is carefully prepared to prevent fermentation. Owning chametz during Passover is also forbidden, not just eating it.
Ashkenazi Jews (those of European descent) follow an additional restriction called kitniyot, which covers legumes, rice, corn, soybeans, and certain seeds like mustard, cumin, and fennel. These foods aren’t actually chametz, and you’re allowed to own them during Passover, but the custom developed because they could be confused with forbidden grains or might have grains mixed in. Sephardi Jews (of Spanish and Middle Eastern descent) never adopted this restriction and eat rice, beans, and corn on Passover without issue. Peanuts fall into a gray area, with some Ashkenazi communities permitting them and others not.
Reading Kosher Certification Symbols
Packaged foods that meet kosher standards carry a certification symbol, sometimes called a hechsher. The most common symbols come from major certifying agencies, each with its own trademarked logo. Letters or words next to the symbol tell you the food’s category. A “D” means dairy. An “M” means meat. The word “Pareve” or no additional letter means the product is neutral. “DE” means the food itself is pareve but was made on dairy equipment. An “F” indicates fish ingredients. A “P” means the product is certified kosher for Passover, meeting the stricter holiday standards.
These symbols appear small, usually near the product name or on the back panel, but they pack a lot of information. For someone keeping kosher, a quick glance at the symbol determines whether a product fits into a meat meal, a dairy meal, or either.