Just like stocks, you can trade currency based on what you think its value is (or where it's headed). But the big difference with forex is that you can trade up or down just as easily. If you think a currency will increase in value, you can buy it. If you think it will decrease, you can sell it. With a market this large, finding a buyer when you're selling and a seller when you're buying is much easier than in in other markets. Maybe you hear on the news that China is devaluing its currency to draw more foreign business into its country. If you think that trend will continue, you could make a forex trade by selling the Chinese currency against another currency, say, the US dollar. The more the Chinese currency devalues against the US dollar, the higher your profits. If the Chinese currency increases in value while you have your sell position open, then your losses increase and you want to get out of the trade.

The logistics of forex day trading are almost identical to every other market. However, there is one crucial difference worth highlighting. When you’re day trading in forex you’re buying a currency, while selling another at the same time. Hence that is why the currencies are marketed in pairs. So, the exchange rate pricing you see from your forex trading account represents the purchase price between the two currencies.
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).
The recovery in risk appetite has caused weakness in the greenback and the yen. The EUR/USD pair is looking bullish due to the bullish recovery in risk sentiment. The resistance levels are 1.1517, 1.1570, and 1.1624. The support levels are 1.1328, 1.1269, and 1.1222. The USD/JPY pair is consolidating with both the currencies looking weak due to risk-on market sentiment. The resistance levels are 107.86, 108.23, and 108.54. The support levels are 106.43, 106.15, and 105.21. […]
The main participants in this market are the larger international banks. Financial centers around the world function as anchors of trading between a wide range of multiple types of buyers and sellers around the clock, with the exception of weekends. Since currencies are always traded in pairs, the foreign exchange market does not set a currency's absolute value but rather determines its relative value by setting the market price of one currency if paid for with another. Ex: US$1 is worth X CAD, or CHF, or JPY, etc.
Forex, also known as foreign exchange, FX or currency trading, is a decentralized global market where all the world's currencies trade. The forex market is the largest, most liquid market in the world with an average daily trading volume exceeding $5 trillion. All the world's combined stock markets don't even come close to this. But what does that mean to you? Take a closer look at forex trading and you may find some exciting trading opportunities unavailable with other investments.
Both types of contracts are binding and are typically settled for cash at the exchange in question upon expiry, although contracts can also be bought and sold before they expire. The forwards and futures markets can offer protection against risk when trading currencies. Usually, big international corporations use these markets in order to hedge against future exchange rate fluctuations, but speculators take part in these markets as well.