The prefix "nano-" refers to a scale that is one billionth of a unit. In the metric system, it is often used to describe measurements in nanometers (nm), which are commonly applied in fields like nanotechnology and materials science. For example, a human hair is about 80,000 to 100,000 nanometers wide, illustrating how small the nano scale is. In nanotechnology, scientists manipulate materials at the atomic or molecular level to create new products and technologies. This can lead to advancements in various areas, including medicine, where nanoparticles are used for targeted drug delivery, and electronics, where smaller components can improve device performance.