Do you really know what cocoa is? Because it is one of cacao's two grandchildren.

The cacao tree - Theobroma (food of the gods) cacao - produces large elliptical pods. Inside are what are sometimes called cocoa beans, but which are neither. They are cacao seeds.

Through fermenting, roasting, grinding, pressing, filtering, and other processes, the seeds are transformed into chocolate liquor (cacao's direct descendant). Chocolate liquor can then be separated into two components, the fat, called cocoa butter, and the dry solid cocoa cakes or "cocoa press," which are subsequently ground into cocoa.

On it's own, pure chocolate liquor is the same thing as unsweetened chocolate.

The word cacao can refer to the tree or the seeds. The word cocoa should really only be used to refer to the ground powder.