Rollover in forex refers to the process of extending the settlement date of an open position by closing the existing position and simultaneously opening a new one for the next settlement date. This often involves interest calculations based on the differences in interest rates between the two currencies in the pair being traded. Traders can earn or pay rollover fees, known as "swap" rates, depending on whether they are holding a long or short position and the associated interest rate differential. Rollover typically occurs at 5 PM EST, and it's essential for traders to understand how it impacts their trading costs and strategies.