Welcome to understanding soccer transfers in the European league.
A transfer occurs when a player under contract moves between clubs. There are a few differences between Europe and US transfers.
Unlike most American sports, trading players is quite rare in Europe. Managers can be transferred as well. And sometimes, a team has no current use for a player, but wants them back for the future.
Example team A would loan the player to team B for a while. That may be a few weeks or a whole season.
FIFA only allows 2 transfer windows per year. Once every summer for up to 12 weeks, and once in the winter for up to 4 weeks. Each country can decide when the window closes just as long as it’s within that time frame.
Once a window’s league is open, a player can transfer in that league, or a league from another country, even if the country’s window has closed.
Now we know what a transfer is, and when it could happen.