In the culinary arts, cardamom is a spice made from the seed pods of various plants in the ginger family. Cardamom has a strong, pungent flavor and aroma, with hints of lemon, mint and smoke.
Cardamom pods contain a number of seeds, but the entire cardamom pod can be used whole or ground. There are two main type of cardamom: black cardamom and green cardamom.
Cardamom is used mainly in Indian cooking as well as Middle Eastern cuisine. In Indian recipes, whole cardamom pods are used in preparing basmati rice and various curries. In Middle Eastern recipes, ground cardamom is used in preparing certain desserts.
If you're using cardamom in a recipe, ideally you'd start with whole cardamom pods. If you buy ground cardamom (i.e. cardamom powder) from the spice section, it won't be as flavorful since the essential oils of the cardamom seed will lose their flavor relatively quickly after the seeds are ground.
Your best bet therefore is to start with whole cardamom pods and toast them in a dry skillet for a few minutes. Let them cool for a minute and then remove the seeds from the pods. Grind the seeds in a mortar and pestle for best results, or you can use a motorized spice grinder (like a coffee grinder).