Nanocelluloses can be classified in three main subcategories on the basis of their dimensions, functions, and preparation methods, which in turn depend mainly on the cellulosic source and on the processing conditions. Herein, the nomenclature is used as cellulose nanocrystal (CNC) and nanofibrillated cellulose (NFC) which are indicated in Table 1. Another type of nanocellulose is the bacterial nanocellulose (BNC) which is synthesized with a bottom-up method from glucose by a family of bacteria, referred to as Gluconoacetobacter xylinius ( Klemm et al., 2011). This type of nanocellulose will not be discussed here as we focus our attention on nanocellulose produced from wood or agricultural/forest crops or residues.