The official birthdate of the smiley is September 19, 1982. It was created by Scott E. Fahlman at Carnegie Mellon University. The two original "glyphs" by Scott were :-) and :-( Since Scott posted his first smiley proposal, MANY other smileys have been devised...
Smileys, also known as emoticons (meaning icons that represent emotion), grew out of the need to display feeling in the two-dimensional, online, written world. When speaking face-to-face (F2F), a person's facial expressions help you understand the meaning of what he or she is saying. Smileys are an attempt to bring that extra nuance to online communications by composing a face out of ASCII characters.
And, lest you think that's all, there are also now assicons and boobiecons... emoticons which highlight other parts of the body! And there are graphical smileys, straight-on smileys, Japanese smileys, special characters and full-on ASCII art, enjoy!
Check out the Original Bulletin Board Thread where the Smiley :-) was Proposed!
Here is NetLingo's special smileys page for a closer head tilting look so you can start using one for yourself 0*-)