Nanocellulose is a material that consists of cellulose nanofibers, which are a chain of cellulose molecules with an elongated tubular shape having a marked length-diameter aspect ratio. The typical trend or magnitude of the diameter is 10 to 20 nanometers and its length is 10 times or more than its diameter. This geometric property of the molecule makes it very sensitive to different fields of application as it is a polymer. The gel substance has a thixotropic behavior. Nanocellulose is classified into three types, microfibrillated cellulose (MFC), nanocrystalline cellulose (NCC) and bacterial cellulose (NBC).

Nanocellulose is basically extracted from any cellulose fiber such as cellulose pulp and can occur in two forms, crystalline or random. It is obtained through a homogenization process or subjection to high pressures, whereby the nanofiber will be amorphous. That obtained through an acid hydrolysis process is called Crystalline Nanocellulose ([NCC] for its acronym in English) and makes up a much more rigid material than that obtained by homogenization.

The term nanocellulose or microfibrillated cellulose was used for the first time in 1977, to designate a translucent gelatinous material, the result of passing cellulose pulp through a homogenizer (called Gaulin-type milk homogenizer at that time) and then impacting it against a rigid surface. This discovery was attributed to the group of researchers Turbak, Snyder and Sandberg who worked in Whipanny, New Jersey for 'ITT Rayonier Labs'.[1]​[2]​

Despite the fact that in the 1950s, ultrasound, hydrolysis, oxidation and also homogenization treatments were already applied to disintegrate cellulose structures.[3]​ It was Turbak's group that arranged the results of the research so that there could be industrial interest in the material.[4]​.

The production of nanocellulose is generally carried out from wood cellulose pulp through homogenization methods (e.g. ultrasonic homogenizers[5]​) and cross-linking, processes through which an amorphous molecule is obtained.

For the production of crystalline nanocellulose, the 'acid hydrolysis' treatment is carried out. Natural cellulose fiber consists of amorphous regions and crystalline regions. The amorphous regions are less dense than the crystalline ones in such a way that when the natural material is subjected to the force of acid hydrolysis (which is greater than that of homogenization and cross-linking), the amorphous regions break up, releasing the crystalline molecules (NCC). There are different types of hydrolysis but in general the 'L/D' aspect ratio (length/Diameter) of crystalline nanocellulose changes with respect to the natural source of cellulose.[6][7]​.