Does any one know the meaning of :-)

[Robert F. Stockdale IV]

I have been using Linux for about 2.5 years now. It has been
almost exclusively.
I'm constantly looking for more information on how to
install, configure and program Linux and any Open Source
software. I keep coming across sequence :-) without ever an
explanation to it's meaning. I would like to know in case
I'm ever asked.
Can anyone help?
Thanks,
Bob Stockdale IV
javabob at localnet.com