For the non-Jewish and those who do not know, the term “kosher” probably sounds like a food ingredient or a way of cooking: there’s kosher salt and the question, “Is that kosher?” In a way, kosher is true that way, but kosher is actually a set of foods that are allowed under Jewish Halakhic law framework. Kosher is thereby part of the Jewish dietary law which is based on the Bible, particularly in the book of Leviticus.
Hence, what determines what is kosher or not? In a way kosher can be quite complicated because there are indeed rules, but to make life simpler for most people, kosher can actually be purchased. There are some basic rules that govern kosher food, and the approach can basically start with meat, dairy and parve or other foods that do not contain meat or dairy.
Meat is considered kosher if it came from an animal that had split hooves and chewed it cud. Hence, cow, goat lamb, chicken, turkey, some ducks and goose are considered kosher. Pig, camel and rabbit are not kosher meat. Another criteria for kosher meat is the way it is slaughtered; it should executed by a shochet or a specialist, and the correct means to cleanse it from blood by soaking and salting it. Another important point is if an animal eats other animals or the food of other animals, they are not kosher.
The rule on dairy is pretty simple. Kosher dairy should come from a kosher animal. However, should dairy is combined with meat, it is no longer kosher.
For parve or other foods, the rules are simple as well. Fruits, grains and vegetables that are prepared in their natural state are kosher. Fish that have fins and scales are kosher as well; examples are salmon, halibut and flounder. Other seafood such as shellfish, underwater mammals, and meat-eating fish are not kosher. Another rule is that should a parve is cooked with meat, it is considered meat; if cooked with dairy, it is dairy. Again, the meat and dairy separation applies to parve.
Kosher, however, does not end in food. It extends to the utensils used and the proper way people should eat meat and dairy, which basically requires a six hour separation for some communities. A kosher kitchen should follow strict rules such as separating the utensils that are used for meat and dairy, and there are strict rules when it comes to materials used for non-kosher food.
The question is, do all Jewish people strictly follow the kosher diet? The answer is no. Many reformed Jews do not follow kosher anymore, but there remains a significant amount of people who abide by these rules. Some follow certain rules such as avoiding non-kosher meat, but in this day and age, it is almost impossible to avoid certain kosher rules, especially when it comes to the separation of meat and dairy, and the maintenance of a kosher kitchen.