The foreign exchange market (also the forex market or FX market) is the global market where currencies trade against each other. It is the largest financial market, run through banks, brokers, liquidity providers, institutions, companies, and traders.
The foreign exchange market is decentralised, with no single central exchange. Currencies trade over the counter through electronic networks across major centres such as London, New York, Tokyo, Singapore, and Sydney, so the market runs around the clock on weekdays.
The market supports international trade, investment, travel, and currency-risk management. Traders use it to speculate on whether one currency will rise or fall against another in pairs such as EUR/USD, GBP/USD, and USD/JPY.
During the London and New York session overlap, when liquidity is deepest, you buy EUR/USD at 1.0850 in the forex market.
If EUR/USD rises to 1.0950, the euro has gained against the US dollar, and you can close the position for a profit.