The forex market is the largest financial market in the world — $7.5 trillion traded every single day. That is 30 times the daily volume of all global stock markets combined. It operates 24 hours a day, 5 days a week, across major financial centers: London, New York, Tokyo, Sydney, and Singapore.
Currency pairs: EUR/USD (most traded), USD/JPY, GBP/USD, and USD/INR. The first currency is the "base"; the second is the "quote." If EUR/USD = 1.10, one euro buys $1.10. Major participants: central banks, commercial banks, hedge funds, corporations, and retail traders. Central banks intervene to stabilize their currencies.
Forex offers leverage up to 50:1 (or higher offshore) — meaning $1,000 can control $50,000 in currency positions. This makes forex both highly profitable and extremely dangerous for retail traders. Studies show that 70-80% of retail forex traders lose money. George Soros famously made $1 billion in a single day by shorting the British pound in 1992.