The functioning of the Forex is not much different from most markets. It is a little more complicated than the stock market, but much simpler than the futures market.

Let's take the example of cross EUR-USD, which is undoubtedly the most interesting, the most liquid and what interests us ... ;-)
Trading operates in batches, in Forex standard, each lot is 100,000 units of the currency in question in this case 100,000 Euros. In the mini-Forex, each lot is only 10,000 units, or 10,000 euros.

The market has a purchase price (bid price), and a selling price (ask price), the normal spread is 3 pips (the Forex USA is the term pip instead of tick), although it is possible to find spreads of 5 and even 6 pips.
Now, to make clear, each pip is 1/10.000 units of currency, or better said: 0.0001 euro here.
As an example, let the bid / ask of the EUR-USD at this time:
Bid (buy): 1.1549
Ask (Sell): 1.1552

The Forex can buy or sell as overdrafts in the future, with the advantage of having no time of maturity and also to negotiate directly with the cash and not a derivative with slightly different.
For example, sometimes when you look at the chart of the DAX and is seeing a movement of intraday reversal, look into the future, and these are well above, with a volatility and a higher speed than the cash .. .
In Forex there are no such problems ... "What you see, is what you get '... ;-)

Another very interesting feature of this market, that is open 24 hours a day ...