FxPro Help Centre - Glossary
A rollover occurs when a position is kept open overnight without being settled (two days being the usual delivery date for Forex). For the position to remain open it must be closed and re-opened so that the scheduled delivery date is deferred for another day. Brokers automatically do this at the same price the position was initially opened at. Rollovers require a swap transaction to take place where the difference between the interest due on the currency borrowed and currency bought is settled.