In Internet e-mail messages and Web discussions, a smiley is a sequence of typed character s that graphically produces the sideways image of someone smiling, like this:
The first use of a smiley is currently attributed to Scott E. Fahlman, who in a posting on Sept. 19, 1982, wrote "I propose the following character sequence for joke markers :-)." Fahlman noted that smile had to be read sideways.
The original smiley led to the creation of many other facial expressions built with keyboard characters as well as the invention of the term emoticon to describe them all.
See emoticon for a long list of them.