Abstract: Nanotechnology is a captivating scientific field with numerous practical applications. The study of nanomaterials and their unique and enhanced capabilities has prompted extensive research into their diverse uses, spanning disciplines from biology and materials science to chemistry and physics. Nanotechnology is expected to play a crucial role in addressing environmental challenges such as sensing, monitoring, mitigation, and power generation. However, it is important to consider the potential environmental impact of nanotechnology, although the specific pathways of such impact have yet to be fully defined. The utilization of nanomaterials in instruments, gadgets, equipment, and other products, as well as the energy required for their production and operation, directly and indirectly influence our environment. In both cases, it is desirable to minimize their impact. Additionally, advancements in nanoscale catalysts, inline and remote detectors, and nano-chemical reactors hold promise for the detection and mitigation of low-level contaminants. Therefore, this chapter focuses on exploring the foundational concepts of nanoscience and nanotechnology as they relate to the field of environmental engineering.