What is a first down?

A first down is a term used in American and Canadian football to indicate that a team has advanced the ball at least 10 yards towards their opponent's end zone. It is the first of four chances, known as downs, that the team has to advance the ball 10 yards. If the team is successful in gaining 10 yards, they are awarded a new set of downs and the process repeats until they either score a touchdown or fail to gain the necessary yardage. A first down is typically signaled by the referee raising one arm with an open palm facing toward the offensive team.