Rum is made with either pure sugar cane juice or molasses mixed with water and fermented. In some cases, yeast is added to aid natural yeasts in the fermenting process.
While rum can be made from sugar cane juice, the majority is manufactured with molasses as its base. Historically, rum was invented in the Caribbean during the early 1600's during the colonial era when plantations grew sugar cane for European consumers. Molasses is a by-product in the production of crystalline sugar for sweetening and it is speculated that a slave perhaps was the first to discover that molasses with water added could ferment due to natural yeasts in the mixture.
Fermented molasses and water or sugar cane juice is then distilled to produce the liquor known as rum. In the distillation process, the fermented liquid is heated. This evaporates the alcohols, which are subsequently re-condensed to produce the pure spirits. The details of the distillation process are particular to each distiller or company, tailoring the spirits to their own recipe.
Some rums, particularly those for sale in the local Caribbean market, are bottled and sold directly from the distillery at varying strengths from 38 to 80 proof. Most rum is aged before sale. Other variations may include the infusion of herbs or fruit juices, the addition of water and also the mixing of different batches from a single distillery.