This document provides an introduction and overview of nanoscience and nanotechnology. It begins with definitions of nanoscience and discusses how behaviors change at the nanoscale level compared to microscale. Examples of nanostructures that exist in nature like DNA and viruses are provided. Methods for building and synthesizing nanostructures both through natural self-assembly processes and human fabrication techniques like atom-by-atom assembly are described. A variety of applications across different fields are mentioned.