:< is an emoticon that can convey sadness, discontent, depression, or the state of boredom between noding and sleep. Akin to its brother, :(, :< is often used in place of :( inside of parentheses because it's more aestheticly pleasing. :< is also used occasionally to express a stronger feeling than :( because the slope of the frown is greater, giving the emoticon a "bigger frown", so-to-speak.