Forex is the world's largest market where currencies are the main commodity. The trading involves currency pairs, i.e. the currencies of two countries. Currencies of some countries are more expensive, whereas others are cheaper. If the value of one currency from a pair is divided by the value of another, you will get a number called a rate or quote.
When participating in transactions on Forex, the trader does not know in advance the amount of profit from a successful forecast. It is calculated proportionally based on the invested amount and the achieved price difference. It turns out the profit is unlimited and depends on how the price of the asset changes.