This document provides an overview of nanoparticles and their application in wastewater treatment. It discusses how nanotechnology offers opportunities to improve water purification through the use of engineered nanoparticles. Nanoparticles have a high surface area to volume ratio and can effectively be used as adsorbents to remove contaminants from wastewater. Different types of nanoparticles like metal nanoparticles, dendrimers, zeolites and carbon nanomaterials have been used for water purification and treatment applications. The document reviews various synthetic methods for producing nanoparticles and their mechanisms for removing pollutants from wastewater.