A native of India, today it is extensively cultivated throughout Asia. The main producers are India and Indonesia. It is often ground and used in a powder form which loses its pungency quite quickly - it is always best to grind pepper freshly.
Black pepper is the dried berry which has been allowed to 'ferment' in the sun, this increases its flavour considerably and is responsible for its colour.
White pepper is the berry which has been husked and dried. The flavour is distinctive but milder than black though it is considerably hotter.
The hotness comes from an alkeloid, piperine.