The spread, in Forex, is the difference between the bid and ask price of a currency pair. For example, if the Bid price of the EUR/USD is 1.16668, and the sell price is 1.16669, the spread will be 0.0001, or 1 pip. In any Forex trade, the value of a currency pair will need to cross the spread before it becomes profitable. To continue with the previous example, if a trader entered a long EUR/USD trade at 1.16668, the trade wouldn't become profitable until the value of the pair was higher than 1.16669.
Since the market is made by each of the participating banks providing offers and bids for a particular currency, the market pricing mechanism is based on supply and demand. Because there are such large trade flows within the system, it is difficult for rogue traders to influence the price of a currency. This system helps create transparency in the market for investors with access to interbank dealing.
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. 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.
Unlike stock markets, which can trace their roots back centuries, the forex market as we understand it today is a truly new market. Of course, in its most basic sense - that of people converting one currency to another for financial advantage - forex has been around since nations began minting currencies. But the modern forex markets are a modern invention. After the accord at Bretton Woods in 1971, more major currencies were allowed to float freely against one another. The values of individual currencies vary, which has given rise to the need for foreign exchange services and trading.