When a swap happens, the first central bank sells currency for a specified amount to the second central bank in exchange for currency at the current exchange rates. The agreement would be to buy back its currency at the same exchange rate on a date in the future. The first central bank uses this currency to lend on its local banks and corporations. On the date agreed upon, the funds would be returned by the first central bank to the lender bank along with interest. The terms of swap are designed to protect both the central banks and are considered to be a meaningful sign of trust between governments.