Nanomaterials are any organic, inorganic, or mixed (organometallic) materials that bear specific properties owing to their miniscule size, which is in the range of 1-100 nanometers (nm). Many types of nanomaterials are known, namely, natural, incidental, engineered, and anthropogenic. Another classification based on the composition of nanostructures divides them into inorganic and organic nanomaterials. The engineered nanomaterials show greater biological activity as compared to larger entities having the same composition and also show greater uptake in living beings. The chief features that influence the toxicity of engineered nanostructures are their size, shape, aspect ratio, surface functionalization, solubility, binding with receptors and proteins, and the propensity to agglomerate. The engineered nanomaterials are sometimes considered as potential threat to soil, animal, and human health which has ignited a debate on the consequences of their indiscriminate use.