Foreign exchange reserves are foreign currency deposits held by central banks. They allow countries to maintain exchange rates and stabilize currencies. Historically, the Bretton Woods system tied currencies to gold and foreign exchange reserves, but this collapsed. Now, central banks use reserves to influence currency values and support domestic monetary policies. The top reserve currencies are the US dollar, euro, yen, and pound sterling. Foreign exchange reserves boost investor confidence and help countries manage debt and economic crises. China has the largest reserves at over $3 trillion. Pakistan currently holds $8.4 billion in reserves.