Spice: any other part of the plant other than the leaf, dried – buds (clove), bark (cinnamon), roots (ginger), berries (peppercorns), aromatic seeds (cumin), stigma of a flower (saffron)
Spices are used in dried form – gain their flavour after drying, when the naturally occurring enzymes are activated (pepper turns black and forms oil piperine, vanilla – fresh is odourless and tasteless)

Whole or ground?
Whole have more shelf life (3 years as opposed to 12-18 months)
Dried are easier to use and impart flavours quicker

Roasted spice?
They have more robust flavour
They are not ideal with delicate fish or vegetable dishes as they can over power the flavours
It is best to add the spices in the beginning of the cooking (with ginger and garlic after the onions have been browned) for 1 minute to temper them. This will start releasing their oil, make spices more digestible (black mustard seed can not be digested without tempering) and starts the roasting process whilst preserving the fresh notes