Keeping kosher is a major commitment. According to Judaism 101, it's more than a series of permissible and forbidden foods, but it also pertains to the preparation of food, the kind of meat you buy, and for many people, the way you keep your kitchen and home. The kosher laws, known in Hebrew as kashrut, are found in Deutoronomy in the Old Testament. There are many foods that can't be eaten (also known as treif), but there are a few basic guidelines you can follow to maintain a kosher existence.

Land Animals

Let's get the big one out of the way: pork. Nothing that comes from a pig is kosher. Other land animals that are not kosher include all varieties of reptiles, rodents or any mammal that lacks cloven hooves and doesn't chew its own cud. That leaves you most of the basic meats modern society prefers such as beef; veal; mutton; lamb; and the most commonly eaten varieties of poultry including chicken, turkey and goose. You can even have goat.

Seafood

Animals from the sea are kosher as long as they have scales and gills and don't feed off the bottom. This eliminates catfish, sand dabs, halibut, shark, eel, swordfish and a number of other swimmers who don't meet the definition. It also means that no variety of shellfish, like shrimp, crab, lobster, mussels, clams, oysters and scallops, is kosher.

Meat and Dairy Combination

The kosher laws prohibit mixing red meat with dairy products. Over time, rabbis expanded application of the rule to all kinds of meats, including poultry. While nothing in the Torah prohibits mixing dairy and poultry, common practice today is to prohibit that as well, according to the Judaism 101 website. Fish, however, can be mixed with dairy, and tuna, salmon, herring and other fish are often present at dairy meals.

Other common American foods that are off-limits to kosher keepers are cheeseburgers, pizza with meat toppings, chili with cheese, cheese steak sandwiches and meat lasagna among many others.