Animals that have split hooves and chew it's cud. Cows, goats, and lambs are kosher for example. Pigs, Rabbits and Squirrels are not.
Kosher Sea creatures:
It must have fins and scales. Tuna and salmon are kosher for example, while catfish shrimp and lobster are not.
Non-predator birds. Chickens, ducks, geese and turkeys are kosher for example, whereas vultures, hawks, eagles and owls are not.
Basic Kosher Concepts
Here are six simple basic rules to keeping Kosher:
Don't eat a non kosher animal (So for example chicken is OK, while pork is not. See Side Column for more info).
Don't eat bugs (So always check your vegetables).
Don't eat blood (So always check your eggs for bloodspots before cooking).
Make sure your wine is Kosher (There are Kosher certification symbols on the bottle to look for, more on that below).
Animals should be slaughtered in a Kosher way: there is a difference between the hamburger sold at a typical grocery store than say a Kosher deli. (For those new to Kosher or without local access to Kosher prepared meats, this may end up being step added later as you progress into Kosher practices).
Don't mix dairy and meat. (Fish is not in the same category as meat in this regards, so fish is OK).
Looking for Kosher Symbols:
Because many store bought foods contain so many different ingredients, many different organizations have come to assist in labeling many food packages with a symbol to tell you if it's Kosher or not. These symbols are called "Hechshers".
Here is some examples to look for: (NOTE: Not all packaging use these)