 Nano simply refers to the size. So if we think about a meter, we can all visualize a meter. If we talk about a kilometer, that means we're thinking about a thousand meters. So kilo means multiply by a thousand. If we think about a millimeter, we're thinking about a thousandth of a meter. A milli means divide by a thousand. And then if we talked about a micrometer, we'd be talking about dividing by a million. And then if we talk about a nanometer, we're talking about dividing by a thousand million, or by ten to the nine. So we divide a meter by ten to the nine, and that gives us a nanometer. So nanomaterials are simply chemical compounds, molecules or arrays of molecules that have a nanometer size. And why that's important is that things can actually change their properties depending on their size.