What do the smell of freshly cut grass, the color purple, the ESPN SportsCenter theme song and the motion of a Lamborghini car door opening have in common? They all have been registered as trademarks.

Trademark-savvy companies may protect and leverage colors, sounds, scents and other unique source identifiers — known as nontraditional marks — to differentiate their products, exploit new marketing opportunities and compete effectively in an increasingly cutthroat marketplace.