Kashrut (also kashruth or kashrus, כַּשְׁרוּת) is a set of dietary laws dealing with the foods that Jews are permitted to eat and how those foods must be prepared according to Jewish law. Food that may be consumed is deemed kosher (// in English, Yiddish: כּשר), from the Ashkenazi pronunciation of the Hebrew term kashér (כָּשֵׁר), meaning "fit" (in this context: "fit for consumption").
Although the details of the laws of kashrut are numerous and complex, they rest on a few basic principles:
Every food that is considered kosher is also categorized as follows:
While any produce that grows from the earth, such as fruits, grains, vegetables and mushrooms, are always permissible, laws regarding the status of certain agricultural produce, especially that grown in the Land of Israel, such as tithes and produce of the Sabbatical year, impact their permissibility for consumption.
Most of the basic laws of kashrut are derived from the Torah's books of Leviticus and Deuteronomy. Their details and practical application, however, are set down in the Oral Torah (eventually codified in the Mishnah and Talmud) and elaborated on in the later rabbinical literature. Although the Torah does not state the rationale for most kashrut laws, some suggest that they are only tests of obedience, while others have suggested philosophical, practical and hygienic reasons.
Over the past century, many kashrut certification agencies have started to certify products, manufacturers and restaurants as kosher, usually authorizing the use of a proprietary symbol called a hechsher on products or issuing a certificate, also called a hechsher, to be displayed by the food establishment, which indicates that they are in compliance with the kosher laws. This labeling is useful in many diets, including for those within religions that expect adherence to the kosher food laws, for example Judaism and the Seventh-day Adventist Church, so too for Muslims since Halal is similar to kosher food compliance, similarly Hindus and people with allergies to dairy foods use the kosher-pareve designation to determine that a food has no meat or dairy-derived ingredients.