This window sees Football League clubs being allowed to bring players in on loan including from the Premiership. The loan window is not open to Premiership clubs, they can only let players leave.
The loan window is vital to Football League clubs as it allows them to bring in cover once needed rather than having a squad too big to financially sustain. However originally designed to help clubs with a genuine shortage of players, the loan window has evolved into a way for Football League clubs to get around the transfer restrictions - allowing them to bring in players from any English club for up to three months.
The loans can often precede a permanent move when the transfer window reopens at the start of next year.