Date and Time / now

now([pollRate])

Returns the current time. The host computer's system clock is used, meaning that if this expression is being evaluated in a running client, the computer running the client's system clock is used. Note that this function is one of the few expression functions that will poll. If you do not specify a pollRate, it will default to 1,000ms. If you do not want this function to poll, use a poll rate of zero.

now()

...returns the current time, updates every second.

dateFormat(now(), "MMM d, h:mm a") 

...returns a string representing the current time, formatted like "Feb 12, 9:54 AM"