The precise mechanisms underlying friction at the nanoscale are still not completely understood. While gears, bearings, and liquid lubricants can reduce friction in the macroscopic world, the origins of micro-and nanoscale friction for small devices require other solutions. This primer explains the concept of friction, in nature and man-made systems, especially at the nanoscale. It then discusses a new class of 'smart' materials with the ability to modulate the friction of a surface.
