Tobacconist University
Simply put, this is the aging process; the very slow process of natural decomposition and chemical changes which occur at lower humidity and temperature levels than Fermentation.  During Añejamiento, tobaccos slowly release ammonia, impurities, and develop.

Tobacco Añejamiento is for leaves and occurs after Fermentation; often this process goes on for years.

Cigar Añejamiento occurs after the cigars are rolled, while they are curated by your Tobacconist, in your personal humidor, all they way up until they are smoked.