How do foreign exchange reserves build up in a country?

Foreign exchange reserves build up in a country primarily through trade surpluses, where exports exceed imports, leading to an influx of foreign currencies. Additionally, countries may accumulate reserves by attracting foreign direct investment (FDI) and portfolio investments, which bring in foreign capital. Central banks also buy foreign currencies to stabilize or influence their domestic currency's value. Lastly, remittances from citizens working abroad contribute to the reserve accumulation.