Rollover Interest (Swap)

Interest credited or charged on a leveraged currency position held overnight, based on the two currencies' interest rates minus a broker markup.

Example

A position might earn 1.20 or cost 1.50 per standard lot for each night it stays open.

Over weeks, rollover costs can equal or exceed the spread, so they matter for any position held beyond a day.

Carry Trade — Borrowing or selling a low-interest currency to hold a higher-interest one, aiming to earn the rate difference.
Bid-ask spread — The gap between the highest price a buyer will pay and the lowest a seller will accept. A cost paid on every round trip.

Price moves, interest differences and leverage - in a market where one side's gain is the other's loss — Forex returns come from exchange-rate moves and interest-rate differences, magnified by leverage, in a market that is roughly zero-sum before costs and negative-sum after them. (12 min)
Appraising one trade: size it from the loss, not from the leverage — Before a currency trade, set how much of your account you will risk, where the trade is wrong, and what the broker and costs add. Position size follows from those, never from the maximum leverage available. (12 min)
Leverage, gaps, the broker itself, and a tax treatment that depends on the product — The biggest forex risks are leverage and sudden gaps. Costs include spreads and overnight financing, and tax treatment varies widely by product and country. (11 min)