Rum distinguishes itself from other spirits by the plant from which it is made.  Rum is made from sugar cane.  Sugar cane is a member of the grass family.  Although it originated in New Guinea, the plant is grown in tropical climates around the world.  

The hard stalks are harvested and then pressed in mechanical mills to extract the sweet juice.   Some distilleries use this fresh juice while others use the by product of the sugar refining process known as molasses as the raw material for the fermentation process.

The addition of yeast to the sugar cane juice or molasses converts the available sucrose to alcohol in a process called fermentation. Typically this takes about a day but some distilleries use yeast that takes as much as ten days. To make other spirits, the starches found in grains must be cooked and then enzymes are used to convert the glucose to sucrose which can be fermented. The result is essentially a fermented sugar cane wine containing only about 10% alcohol by volume.

To concentrate the alcohol in the sugar cane wine, the wine is boiled while the vapor is collected and condensed. The earliest pot stills resembled a tea kettle with a long spout and were capable of distilling only a few liters of alcohol at a time. Modern continuous stills are vertical columns about 10 meters high and are capable of distilling as much as 20,000 liters per day.

In the French islands, spirits made from sugar cane juice are normally distilled to a relatively low distillation purity resulting in a heavier tasting spirit.

Since molasses contains higher amounts of sulphur than sugar cane juice, spirits distilled from fermented molasses are generally distilled to a higher purity to reduce the particles that have been concentrated in the molasses.

Immediately after distillation, the fresh or raw spirits contain small amounts of hydrogen sulfide gas formed during fermentation.  This gives the spirit a hot harsh taste. Although some people prefer fresh rum, most consumers prefer the more elegant taste of an aged spirit. Today, almost all rum is aged in used oak barrels that once held whiskey or bourbon. Aging can last from one to thirty years or more, making rum one of the most varied of the distilled spirits. During the aging process the rum acquires a golden color that changes to a dark brown with time.

The bottled strength of rum depends greatly on consumer preferences. While some rum is bottled at about 40% alcohol by volume, other rums are bottled at the strength at which it was distilled or aged.