Currencies are traded against one another in pairs. Each currency pair thus constitutes an individual trading product and is traditionally noted XXXYYY or XXX/YYY, where XXX and YYY are the ISO 4217 international three-letter code of the currencies involved. The first currency (XXX) is the base currency that is quoted relative to the second currency (YYY), called the counter currency (or quote currency). For instance, the quotation EURUSD (EUR/USD) 1.5465 is the price of the Euro expressed in US dollars, meaning 1 euro = 1.5465 dollars. The market convention is to quote most exchange rates against the USD with the US dollar as the base currency (e.g. USDJPY, USDCAD, USDCHF). The exceptions are the British pound (GBP), Australian dollar (AUD), the New Zealand dollar (NZD) and the euro (EUR) where the USD is the counter currency (e.g. GBPUSD, AUDUSD, NZDUSD, EURUSD).
The profit you made on the above theoretical trade depends on how much of the currency you purchased. If you bought 1,000 units in USD (called a micro lot) each pip is worth $0.10, so you would calculate your profit as (50 pips x $0.10) = $5 for a 50 pip gain. If you bought a 10,000 unit (mini lot), then each pip is worth $1, so your profit ends up being $50. If you bought a 100,000 unit (standard lot) each pip is worth $10, so your profit is $500.
At the end of 1913, nearly half of the world's foreign exchange was conducted using the pound sterling.[24] The number of foreign banks operating within the boundaries of London increased from 3 in 1860, to 71 in 1913. In 1902, there were just two London foreign exchange brokers.[25] At the start of the 20th century, trades in currencies was most active in Paris, New York City and Berlin; Britain remained largely uninvolved until 1914. Between 1919 and 1922, the number of foreign exchange brokers in London increased to 17; and in 1924, there were 40 firms operating for the purposes of exchange.[26]
On 1 January 1981, as part of changes beginning during 1978, the People's Bank of China allowed certain domestic "enterprises" to participate in foreign exchange trading.[51][52] Sometime during 1981, the South Korean government ended Forex controls and allowed free trade to occur for the first time. During 1988, the country's government accepted the IMF quota for international trade.[53]
Foreign exchange trading increased by 20% between April 2007 and April 2010 and has more than doubled since 2004.[59] The increase in turnover is due to a number of factors: the growing importance of foreign exchange as an asset class, the increased trading activity of high-frequency traders, and the emergence of retail investors as an important market segment. The growth of electronic execution and the diverse selection of execution venues has lowered transaction costs, increased market liquidity, and attracted greater participation from many customer types. In particular, electronic trading via online portals has made it easier for retail traders to trade in the foreign exchange market. By 2010, retail trading was estimated to account for up to 10% of spot turnover, or $150 billion per day (see below: Retail foreign exchange traders).
Flights to quality: Unsettling international events can lead to a "flight-to-quality", a type of capital flight whereby investors move their assets to a perceived "safe haven". There will be a greater demand, thus a higher price, for currencies perceived as stronger over their relatively weaker counterparts. The US dollar, Swiss franc and gold have been traditional safe havens during times of political or economic uncertainty.[73]
Trading foreign exchange on margin carries a high level of risk, and may not be suitable for everyone. Before deciding to trade foreign exchange you should carefully consider your investment objectives, level of experience, and risk appetite. Remember, you could sustain a loss of some or all of your initial investment, which means that you should not invest money that you cannot afford to lose. If you have any doubts, it is advisable to seek advice from an independent financial advisor.
Turnover of exchange-traded foreign exchange futures and options was growing rapidly in 2004-2013, reaching $145 billion in April 2013 (double the turnover recorded in April 2007).[57] As of April 2019, exchange-traded currency derivatives represent 2% of OTC foreign exchange turnover. Foreign exchange futures contracts were introduced in 1972 at the Chicago Mercantile Exchange and are traded more than to most other futures contracts.
One of the best ways to learn about forex is to see how prices move in real time and place some fake trades with an account called a paper trading account (so there is no actual financial risk to you). Several brokerages offer online or mobile phone app-based paper trading accounts that work exactly the same as live trading accounts, but without your own capital at risk. There are several online simulators for practicing day trading and honing your forex trading strategy and skills.

Challenge: Banks, brokers, and dealers in the forex markets allow a high amount of leverage, which means that traders can control large positions with relatively little money of their own. Leverage in the range of 100:1 is a high ratio but not uncommon in forex. A trader must understand the use of leverage and the risks that leverage introduces in an account. Extreme amounts of leverage have led to many dealers becoming insolvent unexpectedly.

The foreign exchange market works through financial institutions and operates on several levels. Behind the scenes, banks turn to a smaller number of financial firms known as "dealers", who are involved in large quantities of foreign exchange trading. Most foreign exchange dealers are banks, so this behind-the-scenes market is sometimes called the "interbank market" (although a few insurance companies and other kinds of financial firms are involved). Trades between foreign exchange dealers can be very large, involving hundreds of millions of dollars. Because of the sovereignty issue when involving two currencies, Forex has little (if any) supervisory entity regulating its actions.
An investor can profit from the difference between two interest rates in two different economies by buying the currency with the higher interest rate and shorting the currency with the lower interest rate. Prior to the 2008 financial crisis, it was very common to short the Japanese yen (JPY) and buy British pounds (GBP) because the interest rate differential was very large. This strategy is sometimes referred to as a "carry trade."