Kashrut (also kashruth or kashrus, lang: כַּשְׁרוּת) refers to Jewish dietary laws. Food in accord with halakha (Jewish law) is termed kosher in English, from the Ashkenazi pronunciation of the Hebrew term kashér (כָּשֵׁר), meaning "fit" (in this context, fit for consumption by Jews according to traditional Jewish law). Jews who keep kashrut may not consume non-kosher food, but there are no restrictions on non-dietary use of non-kosher products, for example, injection of insulin of porcine origin.

Food that is not in accordance with Jewish law is called treif ( or treyf, derived from trēfáh). In the technical sense, treif means "torn" and refers to meat which comes from an animal killed by another animal, killed with a dull knife (so felt pain) or having a defect that renders it unfit for slaughter.Fact: date=April 2008

Many of the basic laws of kashrut are derived from the Torah's Books of Leviticus and Deuteronomy, with their details set down in the oral law (the Mishnah and the Talmud) and codified by the Shulchan Aruch and later rabbinical authorities. The Torah does not explicitly state the reason for most kashrut laws, and many varied reasons have been offered for these laws, ranging from philosophical and ritualistic, to practical and hygienic.

Islam has a related but different system, named halal, and both systems have a comparable system of ritual slaughter (shechita in Judaism and Ḏabīḥah in Islam).

The Seventh-day Adventist Church, well known for their health message, expects adherence to the kosher laws, which they refer to as clean foods. Adventists believe that adherence to the laws is not only healthy, but also keeps the body, the metaphorical temple, clean. Many members practice vegetarianism and veganism.

Kosher food

main: Kosher Food

Principles

• Only meat from particular species is permissible:
• Mammals that both chew their cud (ruminate) and have cloven hooves can be kosher. Animals with one characteristic but not the other (the camel, the hyrax and the hare because they have no cloven hooves, and the pig because it does not ruminate) are specifically excluded ( ). (For a comprehensive review of the issue involving the difficulty that neither the hyrax nor the hare are ruminants, see Rabbi Natan Slifkin's "The Camel, the Hare and the Hyrax.")

In 2008, a rabbinical ruling determined that giraffes and their milk are eligible to be considered kosher.

• Birds must fit certain criteria; birds of prey are not kosher. There must be an established tradition that a bird is kosher or similar to one that is before it can be consumed. The turkey, for example, is native to the New World and would therefore not be found under tradition. However, it is similar to a known bird, the "fowl of India" and is therefore acceptable. In general, birds which are hatched with feathers and are able to walk soon after are kosher.
• Fish must have fins and scales to be kosher ( ). Shellfish and non-fish water fauna are not kosher.
• Insects are not kosher, except for certain species of kosher locust (unrecognized in almost all communities).
• That an animal is untamed does not preclude it from being kashrut, but a wild animal must be trapped and ritually slaughtered (shechted) rather than killed some other way to be kosher.
• Meat and milk (or derivatives) cannot be mixed in the sense that meat and dairy products are not served at the same meal, served or cooked in the same utensils, or stored together. Observant Jews have separate sets of dishes, and sometimes different kitchens, for meat and milk, and wait anywhere between one and six hours after eating meat before consuming milk products.