WoW:API date
date ([format [, time]])
It returns a string or a table containing the user's machine's current date and time (or the time represented by time), formatted according to the given string format. If one wishes to supply your own format string, then it uses the same rules as strftime(). The special string *t tells the date() function to return a table.
This is a mirror of the LUA function os.date().
Note that the default format returned when calling the date() function with no parameters will be different depending on whether the game is running on a PC or a Macintosh computer. If you want your addon to be compatible with both systems, you should therefore not use date() without parameters, instead, use
date("%m/%d/%y %H:%M:%S")
to display the date in the default PC format
-or-
date("%a %b %d %H:%M:%S %Y")
to display the date in the default Macintosh format