In boxing, rounds are scored by judges. In Olympic scoring, five judges score based on punches, electronically registering each punch. In US Professional Scoring, three judges score each round, usually giving ten points to the winner and nine to the loser with 10-10 for a tie.
Boxing does not have one singular international ruling body. Multiple kinds of boxing exist across the world. Two main kinds of scoring in boxing prevail, however. The Olympic method is used in the Olympic games and for some other amateur boxing. The round scoring system is used in professional boxing such as the World Boxing Association (WBA), World Boxing Organization (WBO) and more such organizations.
Olympic Scoring is based, not on rounds, but on punches landed. Five judges sitting ringside each have electronic buttons. When the fighters land a punch to their opponents head gear and midsection, the judges press their button to register the punch having landed. Punches to the arms, below the belt, or back of the head will not be registered. In order for the punch to be officially counted, at least three out of the five judges have to press their buttons, registering a punch. At the end of the fight, three rounds of three minutes each, the fighter with the most punches landed will be the winner.
Scoring in professional boxing such as WBO, WBA and WBC is not based on amount of punches but instead based on rounds. Most fights go for twelve rounds. A group of three ringside judges score each round, choosing a winner and a loser. Usually the winner is awarded ten points while the loser is awarded nine points. If the judges believe the round to be a tie they will score it ten to ten. Knockdowns too can change the score. If the losing fighter is knocked down once in a round the score will be 10-8. Twice makes it 10-7 and so on. Points can be deducted from fighters for illegal hits, to the back of the head or below the belt for instance, even if the fighter wins the round.