Garam masala, which means "hot spice" in Hindi, is an Indian spice blend usually used for finishing dishes throughout northern India. Despite the name, garam masala is not especially spicy, and the "hot" may refer to the fact that the spices are toasted before grinding. The recipe changes from region to region, with each household adding its own touch. However, some of the common elements are peppercorns, cumin, cinnamon, cardamom, coriander, cloves, and bay leaves.
As a rule, garam masala is added at the last step of cooking, almost like a fresh herb. If cooked too long, it becomes bitter.
Garam masala is available on some grocery store spice racks as well as in Indian markets, but for the best flavor, try toasting and grinding your own.
If you're buying ready-made garam masala, buy from a source that has steady turnover, and only buy what you'll use in a couple of months.