Forex, short for foreign exchange, is a decentralized global market for trading national currencies against one another. It is the largest and most liquid financial market in the world, operating 24 hours a day, five days a week. Participants include banks, financial institutions, corporations, governments, and individual traders who speculate on currency price movements. The market is influenced by various factors, including economic indicators, geopolitical events, interest rates, and market sentiment, making it a complex environment for trading.