I recently read an interesting article in The New Yorker magazine about paper jams in printers. Below is an excerpt from the article:

"In the largest sense, jamming is a problem in a field called tribology - the study of friction, lubrication, and wear between interacting surfaces. . . . (The term 'tribology' . . comes from the Greek verb 'to rub.') . The smooth functioning of the world depends on invisible tribological improvements."