When is something so small that we call it 'Nano'?

But it said "Nano"on the box
"The much-hyped future of nanotech - medical miracles! pure water and air! space elevators! - is nowhere in sight. But so-called nano products for the home are flooding the marketplace. Few are truly tiny and self-assembling; some don't even come close. Here's a guide to which household wonders are nano, and which are not".

Nothing to add here..