What do the yellow, red and black cards mean?

Same idea as soccer, with fencing's own flavor. Yellow card: a warning, no touch awarded, for first offenses like starting before 'fence', turning your back, covering target with your other hand, or gear problems like arriving with a non-working weapon. Red card: your opponent gets a free touch, for repeating a yellow-card offense, or for more serious ones that skip yellow entirely (a violent or dangerous action, refusing to obey the referee). Black card: expulsion from the event, reserved for serious misconduct: cheating, deliberately dangerous fencing, abusing officials, unsportsmanlike behavior. Black cards are rare and memorable.

Two details that surprise new families: cards can be given for things that feel administrative, showing up without a spare weapon at some events, or a coach yelling from the sidelines can even draw cards against the fencer's side. And a red card in the last second of a tied bout genuinely decides matches, which is why experienced fencers are careful about the 'small' offenses like early starts.

There's also a group of penalties for the OTHER fencer's benefit you'll hear called differently, like the referee annulling a touch scored during an infraction. If a call confuses you at an event, it's completely normal to (politely, between bouts) ask the referee what the card was for. Good refs explain; kids learn the rules fastest this way.