Rum is made by fermenting, then distilling sugarcane molases or sugarcane juice, usually the as a by-product of sugar manufacturing.

Today, rum is usually made in one of three methods:
  1. Fermenting sugar cane juice
  2. Ferment the juice of molasses
  3. Fermenting the concentrating syrup from the sugar cane juice
Rums are made in various grades:

Light Rum
(typically from Cuba or Puerto Rico) and these are commonly used in cocktails.
Dark or Golden Rum
(typically from Jamaica) is heaver fuller flavored rum and is e commonly used for cooking, although some people use in in cocktails. Dark rum has a stronger taste.
All rums start out as totally clear spirits, but get their color and flavor from aging them in casks or barrels. Aging in a cask or wooden barrel is a legal requirement for any rum.

The taste of the rum is impacted by the climate and the soil the sugar product grows in. So rum from different areas will taste different, even though they are distilled the same way.