There is no minimum deposit or minimum balance required to open an OANDA account for forex trading. You only need make sure to have enough equity to open positions of sizes you are comfortable with including margin requirements. You can calculate the margin required when you open a position in a currency pair using the OANDA Forex Margin Calculator .
Major Currency — currencies from the world’s most developed economies including Europe, Japan, Canada, and Australia — represent the most heavily traded and liquid currency markets for any forex trader. A major currency pair is created when one of these currencies is traded against the U.S. dollar. Examples include Euro vs. the U.S. Dollar (EUR/USD) and the U.S. Dollar vs. the Canadian Dollar (USD/CAD). Their availability on a forex brokerage is essential.
Trading in the euro has grown considerably since the currency's creation in January 1999, and how long the foreign exchange market will remain dollar-centered is open to debate. Until recently, trading the euro versus a non-European currency ZZZ would have usually involved two trades: EURUSD and USDZZZ. The exception to this is EURJPY, which is an established traded currency pair in the interbank spot market.
The forex market is the largest market in the world with an average trading value over $5 trillion per day. It has no centralized marketplace where transactions are conducted. Forex trading is carried out electronically over-the-counter (OTC), meaning that all trading transactions are performed via computer by traders and other market participants over the world.
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.
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.