A trade system is a system in which two or more teams exchange specific players between agreements. It is a system that is generally operated in leagues with a draft system. FA refers to a system in which a player who joins a team can freely move to another team after a set contract period.

The system is very active in the four major professional sports, namely professional baseball, professional basketball, professional soccer, and professional volleyball.

As of 2024, if you are a first-team player, the registration period must exceed one regular season, based on 145 days. You have to play a total of eight regular seasons to qualify for the first FA, and after that, you have to go through four regular seasons to qualify for multiple FA qualifications.

Professional volleyball players who graduated from high school in the women's division will be given the first FA qualification if they play on one team for six years, and from the second, they can be obtained every three years.

For this reason, Stove League should also pay attention to the fact that star players of each club have fun changing uniforms during the season when they become free agents. Another beauty of the professional league is that they meet their old team as an enemy and have blood clots.

The professional basketball PBA launched a team league following an individual tour, introducing a match system for each club currently introduced in most professional leagues. It is uncommon for a team-based billiard system, which was launched by middle-sized and large companies as sponsors, setting up a club, and setting up a regular season.

PBA unveiled its team league system for the 20-21 season for the first time. Including the 23-24 season that ended last month, PBA has been playing team league games for a total of four seasons.

The PBA Team League, which started with six clubs (Shinhan Financial Investment, SK Rent-a-Car, Blue One Resort, Welcome Savings Bank, TS Shampoo, and Crown Haitai) in its first season, is now operated with nine clubs (SK Rent-a-Car, Blue One Resort, Welcome Savings Bank, Crown Haitai, Huons, SY, High One Resort, Hana Card and NH Nonghyup Card). There is a possibility that the number will increase to 10 starting from the 24-25 season.

There are cases of players changing their uniforms during this period, but not many. There are cases where a team moved to another team due to the disbandment or release of a club, or was eliminated from the first part of the previous season and was released from the existing team and returned to find a new team.