**3. Nanostructures of inorganic materials**

A major feature that discriminates various types of nanostructures is their dimensionality (**Figure 3a–d**). The word "nano" stems from the Greek word "nanos," which means dwarf. This word "nano" has been assigned to indicate the number 10<sup>−</sup><sup>9</sup> , i.e., 1 billionth of any unit [17]. It is believed that the size of particle has inverse relation with the surface area and reactivity thereby, nanoparticles reveal superior practical potential over micron-sized one.
