Well, Mike, nowadays there's much talk about nanometer. But what on earth is it?
Nanometer is a length scale. It's one billionth of a meter, roughly ten times the size of an individual atom.
Hmm. . . it's hard to figure out the exact size, I'm afraid.
Well, let's make it this way. For comparison , 10 NM is 1000 times smaller than the diameter of a human hair. There are as many nanometers in an inch as there are inches in 400 miles.