What is post time in horse racing?

Strictly speaking, post time is the when all the horses are “at post,” or ready to start.

Once upon a time, that meant they were lined up behind some sort of temporary barrier like a rope at the beginning of a race. 

But today the term is more often used to refer to the time of day a race is scheduled to be to be run or as a warning by racetrack announcers that there is little time left to wager. Read more about picking the winner.