The primary ingredient in almost all rum is a base of sugarcane molasses, which is fermented with yeast before the mixture is distilled and aged. Molasses is cheaper than sugar, and according to Flaviar, “The ethanol [from sugarcane] has been found to burn cleaner than fossil fuels."
The underlying flavor profile of rum is of sweet, toasted sugar, although where the sugarcane is grown causes flavor varietals and differing notes in the rum itself, too. There are eight distinctive styles of rum, each with its own flavor profile, color, strength, body, and additional spices.
In 2017, Food & Wine published a deep-dive into rum's problematic past, noting that it "has a fraught history mired in colonialism, slavery, economic oppression, and organized crime." Today, though, changes are being made to diversify the rum industry and make amends for its hateful, painful history.