Native to China and India ginger is used fresh, dried then powdered and preserved or pickled. Though often called root ginger it is actually a rhizome (i.e. a horizontal plant stem that is often found underground).
Fresh ginger has a zesty fresh flavour. It is peeled then sliced, diced or pounded. It is almost ubiquitous in Cantonese cooking and much used in stir frys and other dish throughout South-East Asia.
Powdered ginger is softer in taste but quite aromatic. It is mostly used in countries which don't produce fresh ginger.
There are a number of types of preserved and pickled ginger whose flavour and use vary with the country of origin.
Ginger is also used medicinally.