The transfer window is the period during the year in which a football club can transfer players from other countries into their playing staff. Such a transfer is completed by registering the player into the new club through FIFA. "Transfer window" is the unofficial term commonly used by the media for the concept of "registration period" as described in the FIFA Regulations on the Status and Transfer of Player. According to the rules, each national football association decides on the time (such as the dates) of the 'window' but it may not exceed 12 weeks. The second registration period occurs during the season and may not exceed four weeks.