Etymology
Old English piper, from the Sanskrit pippali (berry) via Greek and Latin.

Black pepper
Black pepper is stronger than white. It is often used coarsely-ground from a pepper mill to season grilled meats.

White pepper
White pepper is much milder. It is used in white sauces, cream soups, for seasoning poultry, etc., in order to avoid adding black specks to pale foods.

Green peppercorns
These are fresh peppercorns, often from Madagascar, thus their nickname "Madagascar pepper." Mild and refined, they are used to make green peppercorn sauces for grilled beef.

Pink peppercorns
Despite their name, these are not true members of the pepper family. They are pink berries having a slightly peppery flavor.

Gourmetpedia
(kali mirchi) - In India, peppercorns are used whole, heated for a few seconds in a non-stick pan before being added to a dish or preparation.