Currency prices can only fluctuate relative to another currency, so they are traded in pairs. Take two of the most common currency pairs, the EURUSD (the price for euros in US dollars) and the GBPUSD (the price for the British pound in US dollars).

High Leverage
The idea of margin (leverage) and floating loss is another important trading concept and is perhaps best understood using an example. Most retail Forex market makers permit 100:1 leverage, but also, crucially, require you to have a certain amount of money in your account to protect against a critical loss point. For example, if a $100,000 position is held in EURUSD on 100:1 leverage, the trader has to put up $1,000 to control the position. However, in the event of a declining value of your positions, Forex market makers, mindful of the fast nature of forex price swings and the amplifying effect of leverage, typically do not allow their traders to go negative and make up the difference at a later date.

In order to make sure the trader does not lose more money than is held in the account, forex market makers typically employ automatic systems to close out positions when clients run out of margin (the amount of money in their account not tied to a position). If the trader has $2,000 in his account, and he is buying a $100,000 lot of EURUSD, he has $1,000 of his $2,000 tied up in margin, with $1,000 left to allow his position to fluctuate downward without being closed out.

Typically a trader's trading platform will show him three important numbers associated with his account: his balance, his equity, and his margin remaining. If trader X has two positions: $100,000 long (buy) in EURUSD, and $100,000 short (sell) in GBPUSD, and he has $10,000 in his account, his positions would look as follows: Because of the 100:1 leverage, it took him $1,000 to control each position. This means that he has used up $2,000 in his margin, out of a $10,000 account, and thus he has $8,000 of margin still available.

With this margin, he can either take more positions or keep the margin relatively high to allow his current positions to be maintained in the event of downturns. If the client chooses to open a new position of $100,000, this will again take another $1,000 of his margin, leaving $7,000. He will have used up $3,000 in margin among the three positions. The other way margin will decrease is if the positions he currently has open lose money. If his 3 positions of $100,000 decrease by $5,000 in value (which is fairly common), he now has, of his original $7,000 in margin, only $2,000 left.

If you have a $10,000 account and only open one $100,000 position, this has committed only $1,000 of your money plus you must maintain $1,000 in margin. While this leaves $9,000 free in your account, it is possible to lose almost all of it if the speculation loses money.

Technical FOREX trading considerations: As in other markets, the accumulated price movements in a currency pair such as EUR/USD can form apparent patterns that traders may attempt to use. Many traders study price charts in order to identify such patterns.