For instance, if you opened a long trade on the GBP/USD currency pair, and the pair increased in value, the price limit at which the trade should close (the stop loss) would climb alongside the price of the currency pair. If the value of the GBP/USD then started to fall, the trade would be closed as soon as it hit your stop loss, preserving any profits you had made beforehand.
The foreign exchange market – also called forex, FX, or currency market – was one of the original financial markets formed to bring structure to the burgeoning global economy. In terms of trading volume it is, by far, the largest financial market in the world. Aside from providing a venue for the buying, selling, exchanging and speculation of currencies, the forex market also enables currency conversion for international trade settlements and investments. According to the Bank for International Settlements (BIS), which is owned by central banks, trading in foreign exchange markets averaged $5.1 trillion per day in April 2016.
Factors like interest rates, trade flows, tourism, economic strength and geopolitical risk affect supply and demand for currencies, which creates daily volatility in the forex markets. An opportunity exists to profit from changes that may increase or reduce one currency's value compared to another. A forecast that one currency will weaken is essentially the same as assuming that the other currency in the pair will strengthen because currencies are traded as pairs.
Forex is the one financial market that never sleeps, meaning you can trade at all hours of the day (or night). Unlike the world's stock exchanges, which are located in physical trading rooms like the New York Stock Exchange or the London Stock Exchange, the Forex market is known as an 'Over-the-counter market' (or OTC). This means that the trades take place directly between the parties holding the currencies, rather than being managed via an exchange.
Spot for most currencies is two business days; the major exception is the U.S. dollar versus the Canadian dollar, which settles on the next business day. Other pairs settle in two business days. During periods that have multiple holidays, such as Easter or Christmas, spot transactions can take as long as six days to settle. The price is established on the trade date, but money is exchanged on the value date.
A spot transaction is a two-day delivery transaction (except in the case of trades between the US dollar, Canadian dollar, Turkish lira, euro and Russian ruble, which settle the next business day), as opposed to the futures contracts, which are usually three months. This trade represents a “direct exchange” between two currencies, has the shortest time frame, involves cash rather than a contract, and interest is not included in the agreed-upon transaction. Spot trading is one of the most common types of forex trading. Often, a forex broker will charge a small fee to the client to roll-over the expiring transaction into a new identical transaction for a continuation of the trade. This roll-over fee is known as the "swap" fee.

In the futures market, futures contracts are bought and sold based upon a standard size and settlement date on public commodities markets, such as the Chicago Mercantile Exchange. In the U.S., the National Futures Association regulates the futures market. Futures contracts have specific details, including the number of units being traded, delivery and settlement dates, and minimum price increments that cannot be customized. The exchange acts as a counterpart to the trader, providing clearance and settlement.