Smile :-), it's your birthday
This was published on a personal blog I ran during the nillies, it’s included here as a historical archive. Links and images may be broken, it’s been a while.
Last week the Smiley :-) turned 25. Happy birthday and congratulations! It was proposed by Scott E Fahlman in a post to a “Bulletin board” at Carnegie Mellon University the 19th of September 1982. Scott proposed its use to mark humorous or sarcastic remarks so they wouldn’t be misunderstood.
These two pages have more info on the origin of the Smiley