A nanometer is a unit of measurement in the metric system, equal to one billionth of a meter (10^-9 meters). It is commonly used to describe extremely small objects, such as atoms and molecules. For context, a human hair is about 80,000 to 100,000 nanometers wide, illustrating just how tiny a nanometer really is. Nanometers are crucial in fields like nanotechnology, which involves manipulating matter at the atomic and molecular scale. This technology has applications in various areas, including electronics, medicine, and materials science, enabling the development of smaller, more efficient devices and innovative treatments.