Some things in our universe are so extreme their scale is unfathomable. Looking to one end, we have entities in our universe such as galaxies or supermassive black holes which are so vast, that they are measured in light-years (the distance light travels in one earth year). For example, the largest supermassive black hole, TON 618, is about 320,000 light-years across which is about 3.027e18 kilometers, whereas the circumference of our earth is only about 40,000 kilometers.
But not only is one polar end of this universal scale unimaginable in size, but the other is as well. From light-years, through kilometers, all the way to nanometers. Once again, it’s extremely difficult to comprehend the size of a nanometer. But, for example, the width of a plain piece of paper is about 100,000 nanometers thick. A piece of hair is about 50,000 nanometers wide. And now what’s left to compare nanometers to? Atoms and molecules, something unable to be seen on their own by the naked eye, are measured in nanometers which is about 1e-10 kilometer. So basically, a nanometer is a unit of measurement equal to about a billionth of a meter that is used to measure items on the subatomic scale.
So why should we care about something so so so small? Well, many processes occur at the nanoscale, and research at this level isn’t only in smaller dimensions, but it allows scientists to utilize the unique physical, chemical, mechanical, and optical properties of materials that naturally occur at that scale.