According to the Bank for International Settlements, the preliminary global results from the 2019 Triennial Central Bank Survey of Foreign Exchange and OTC Derivatives Markets Activity show that trading in foreign exchange markets averaged $6.6 trillion per day in April 2019. This is up from $5.1 trillion in April 2016. Measured by value, foreign exchange swaps were traded more than any other instrument in April 2019, at $3.2 trillion per day, followed by spot trading at $2 trillion.[3]
The foreign exchange market is unique for several reasons, mainly because of its size. Trading volume in the forex market is generally very large. As an example, trading in foreign exchange markets averaged $5.1 trillion per day in April 2016, according to the Bank for International Settlements, which is owned by 60 central banks and is used to work in monetary and financial responsibility. 
One of the most unique features of the forex market is that it is comprised of a global network of financial centers that transact 24 hours a day, closing only on the weekends. As one major forex hub closes, another hub in a different part of the world remains open for business. This increases the liquidity available in currency markets, which adds to its appeal as the largest asset class available to investors.
Risk/reward signifies how much capital is being risked to attain a certain profit. If a trader loses 10 pips on losing trades but makes 15 on winning trades, she is making more on the winners than she's losing on losers. This means that even if the trader only wins 50% of her trades, she will be profitable. Therefore, making more on winning trades is also a strategic component for which many forex day traders strive.
Currency and exchange were important elements of trade in the ancient world, enabling people to buy and sell items like food, pottery, and raw materials.[9] If a Greek coin held more gold than an Egyptian coin due to its size or content, then a merchant could barter fewer Greek gold coins for more Egyptian ones, or for more material goods. This is why, at some point in their history, most world currencies in circulation today had a value fixed to a specific quantity of a recognized standard like silver and gold.

Currency speculation is considered a highly suspect activity in many countries.[where?] While investment in traditional financial instruments like bonds or stocks often is considered to contribute positively to economic growth by providing capital, currency speculation does not; according to this view, it is simply gambling that often interferes with economic policy. For example, in 1992, currency speculation forced Sweden's central bank, the Riksbank, to raise interest rates for a few days to 500% per annum, and later to devalue the krona.[82] Mahathir Mohamad, one of the former Prime Ministers of Malaysia, is one well-known proponent of this view. He blamed the devaluation of the Malaysian ringgit in 1997 on George Soros and other speculators.

The possibility of losing your investment is high, so it is advisable to only use risk capital (money that you can afford to lose) when engaging in Forex trading. The Forex market offers high levels of leverage to traders. Leverage has both the possibility of high returns and high losses, and should only be used with discretion. Be disciplined and don't be tempted to overtrade.

One unique aspect of this international market is that there is no central marketplace for foreign exchange. Rather, currency trading is conducted electronically over-the-counter (OTC), which means that all transactions occur via computer networks between traders around the world, rather than on one centralized exchange. The market is open 24 hours a day, five and a half days a week, and currencies are traded worldwide in the major financial centers of London, New York, Tokyo, Zurich, Frankfurt, Hong Kong, Singapore, Paris and Sydney—across almost every time zone. This means that when the trading day in the U.S. ends, the forex market begins anew in Tokyo and Hong Kong. As such, the forex market can be extremely active any time of the day, with price quotes changing constantly.