It has been 25 years since Carnegie Mellon professor Scott Fahlman, shown in his home office on Monday, first used a horizontal "smiley face" in a computer message. To mark the date, Fahlman and his colleagues are starting a contest for innovation in technology-assisted, person-to-person communication.

PITTSBURGH — It was a serious contribution to the electronic lexicon.

Twenty-five years ago, three keystrokes — a colon followed by a hyphen and a parenthesis — were first used as a horizontal "smiley face" in a computer message by Carnegie Mellon University professor Scott Fahlman, the university said.

To mark the anniversary Wednesday, Fahlman and his colleagues are starting an annual student contest for innovation in technology-assisted, person-to-person communication. The Smiley Award carries a $500 cash prize.

Language experts say the smiley face and other so-called emoticons, or emotional icons, have given people a concise way of expressing sentiments in e-mail and other electronic messages that otherwise would be difficult to detect.

Fahlman posted the emoticon in a message to an online electronic bulletin board at 11:44 a.m. on Sept. 19, 1982, during a discussion about the limits of online humor and how to denote comments meant to be taken lightly.

"I propose the following character sequence for joke markers: :-)," wrote Fahlman. "Read it sideways."

The suggestion gave computer users a way to convey humor or positive feelings with a smile — or the opposite sentiments by reversing the parenthesis to form a frown.

Carnegie Mellon said the smileys spread from its campus to other universities, businesses and eventually around the world as the Internet gained popularity. Variations, such as the "wink" that uses a semicolon, emerged later.

"It has been fascinating to watch this phenomenon grow from a little message I tossed off in 10 minutes to something that has spread all around the world," Fahlman said in a university statement.

"I sometimes wonder how many millions of people have typed these characters, and how many have turned their heads to one side to view a smiley, in the 25 years since this all started."

Amy Weinberg, a University of Maryland linguist and computer scientist, said emoticons such as the smiley were "definitely creeping into the way, both in business and academia, people communicate."

"In terms of things that language processing does, you have to take them into account," she said.