The game of tennis traces its roots back to medieval France, and although history cannot exactly pinpoint the origin of tennis' scoring system, the modern version of tennis scoring  was finalized in the Victorian period. 

Here is a breakdown of the point system:

• Love = 0 points 
• 15 = the first point
• 30 = the second point
• 40 = the third point
• All = tied score
• Deuce = 40-40
• Ad-in = Server wins deuce point 
• Ad-out = Receiver wins deuce point
   

After players or teams reach deuce, the next score will either be Ad-in or Ad-out. "Ad" is short for advantage, meaning that player with the "ad" score is at an advantage. If the score is Ad-in, that means the server won the deuce point. If the score is Ad-out, it means the receiver won the deuce point.

If the player that has advantage wins the next point, that means they have won the game. If the player that does not have the advantage wins the point, the score goes back to deuce (40-40), and play continues until one player or team wins by two points. 

The tie-breaker will start with the next server getting one serve from the deuce court. Following that, the serve will go to the other competitor and they will begin from the AD court. After the initial point, the serve in the tie-breaker will then be rotated every two points, starting from the AD court. Every sixth point, the players will switch sides. The first player to reach seven points and win by two will win the tie-breaker and the set.

If the set score has reached 6-6, and it is the deciding set in a best-of-three or best-of-five-set match, the set will be played out until one competitor has a two-game lead in the final set. No tie-breaker will be used.
 

Every tennis match is comprised of sets, and each set is comprised of games. 

Game

A game score begins at love-all, or 0-0. The first point is called 15, so if the server wins the point, the score becomes 15-love. If the receiver wins the point, the score becomes love-15. The server's score is always given first. The second point for a player or side is called 30, followed by 40. The next point can win the game, but only if the opposing player has 30 or less, because games must be decided by at least two points. If the players both reach 40, the score is termed "deuce." The next point gives one player the advantage. On the following point, the player with the advantage tries to win the game by getting two points ahead, while the trailing player tries to even the score again at deuce. The first player to reach advantage, then score the next point, wins the game.

After every game the server will change, and after every odd game, the players will switch sides.

Set

To win a set, one must win a total of six games before their opponent does. If the set score reaches 5-5, the competitors will play to seven while still having to win by two. If the set score reaches 6-6 -- and the set is not the deciding one in a best-of-three or best-of-five-set match -- the next game will go to a tie-breaker.

Match

Matches will be a best-of-three format. The first competitor to win two or three sets, respective to the match format, will win the match.