**6. Conclusion and future perspective**

The need for environmentally-friendly and stable nanomaterial that would be compatible with biological systems have prompted researchers into the production of nanoparticles. This chapter gives general knowledge on nanoparticles, their classification, merits and demerits, several synthesis and characterization techniques. Nanoparticles have economical and simple manufacturing processes that are classified into top-down method, bottom-up approach, chemical synthesis, biological method, and mechanical process. Several characterization methods of nanoparticles are geared towards understanding the morphological, structural, optical, size, mechanical, and physiochemical features. Each property is obtainable from different machines and using different techniques. The synthesis and characterization methods employed greatly influence the obtained features of the nanoparticles. Nanoparticles find useful application in medicine, drug delivery, cosmetics, optical devices, electronics, solar cell devices etc.
