Here’s just a small section of Michael Dietsch’s awesome write up on rum. Must read for anyone enjoy’s rum, but doesn’t really know much about it.
Rum Styles
White/Light/Silver:
Light bodied, crisp, and subtle in flavor, these rums are highly mixable. They marry very well with fruit flavors, so theyre excellent for daiquiris and piña coladas. A common misconception about white rum is that its unaged. White rum is aged in oak barrels for a short period of time to smooth out the flavors; its then charcoal filtered to remove color. Bacardi is the best known example of a white rum; other brands include Don Q, Flor de Caña, and Banks Five Island.
Gold/Oro/Ambre:
Medium bodied and a little stronger in flavor than light rums, gold rums are aged in oak barrels. Like light rums, they mix well into fruity cocktails. Bacardi, Don Q, and Ron Rico are commonly available brands.
Dark/Black:
Full-bodied, with rich caramel flavors, these rums are usually pot-stilled and aged for long periods. Used in tiki preparations such as the Mai Tai, the best of these rums are also sippable on their own, neat or on ice. Mount Gay, Appleton, Goslings, and Ron Zacapa are common brands.
Rhum agricole:
Full-bodied rums, made from sugarcane juice instead of molasses. As with molasses-based rum, agricoles range the color spectrum, from white to gold to dark. Agricoles are often funky and have floral and vegetal aromas and flavors. Brands include Rhum Clement, Rhum J.M., Neisson, and La Favorite.
Other Terms
You may encounter other terms when shopping for rum. Heres a grab-bag glossary of rum words:
Naval rum:
A dark, full-bodied rum in the style of that formerly given to members of the British Navy. Normally proofed at 50% abv or higher.
Single barrel:
Most rums on the market are blended products. To achieve consistency in taste from release to release, manufacturers blend rums from different barrels to get the balance of flavors right. A single-barrel rum comes from just one barrel, and the rum may taste different from barrel to barrel.
Overproof:
Refers to rums with an ABV over a standard value, usually 120 proof, or 60% ABV.
You absolutely should read the whole thing at The Serious Eats Guide to Rum | Serious Eats: Drinks.