Just one smile can brighten up a room. A smile is a universal symbol: It's one of our first means of communication as babies and requires no translation across cultures. Although smiling may seem like a uniquely human trait, it's not uncommon to see smiles from animals -- or even inanimate objects. Thanks to the proliferation of Internet communication, smiles have even become a part of our written language.
Last week for the Mashable Photo Challenge, we honored the 30th anniversary of the emoticon by asking our readers to submit photos that represented a smile.