Cumin seeds, or whole cumin, is a key ingredient in Indian Cookery, and is used extensively in almost every dish along with coriander and the other garam masala spices. Typically, cumin seeds are crushed or ground immediately before cooking, in order to release the flavours at exactly the correct time.
Of course, cumin powder is also available for convenience... but the cumin seeds below are preferable for an authentic flavour.
Using Cumin Seeds:
Crush immediately before adding to a curry.
Use around 1-2 heaped tablespoons per person (10g to 20g).
The flavour is intensified if you heat the cumin seeds in a pan immediately after crushing.