All About Rum

There’s nought no doubt so much the spirit calms as rum and true religion" – Lord Byron Fifteen men on a dead man’s chest, Yo, ho, ho and a bottle of Rum. – 17th century 401(k) savings plan for buccaneers

Rum, and its fraternal twin, cane spirit, are made by distilling fermented sugar and water. This sugar comes from the sugar cane and is fermented from cane juice, concentrated cane juice, or molasses. Molasses is the sweet, sticky residue that remains after sugar cane juice is boiled and the crystallized sugar is extracted.
Most Rum is made from molasses. Molasses is over 50% sugar, but it also contains significant amounts of minerals and other trace elements, which can contribute to the final flavor. Rums made from cane juice, primarily on Haiti and Martinique, have a naturally smooth palate.
Depending on the recipe, the "wash" (the cane juice, or molasses and water) is fermented, using either cultured yeast or airborne wild yeasts, for a period ranging from 24 hours for light Rums up to several weeks for heavy, full varieties.

Source: Tastings.com