The simple answer is money. FOREX trading is the simultaneously buying of one currency and selling of another. Currencies are traded through a FOREX brokers or dealers and are traded in pairs, for example euro and the US dollar (EUR/USD) or the British pound and the Japanese Yen (GBP/JPY)
Because you are not buying anything physically, this kind of trading can be confusing, thinking of buying a currencies as buying a share in a particular country.
When you buy say Japanese Yen you're in effect buying a share in Japanese economy, as the price of the currency is a direct reflection of what the market thinks about the current and the future health of the Japanese economy and this also applied to cryptocurrency. You can download cryptocurrency trading chart
In general, the exchange rate of a currency versus other currencies is a reflection of the condition of that country's economy, compared to the other countries economics. 
Unlike other financial markets like New York Stock exchange, Canada stock exchange, the forex market has a neither a physical location nor central exchange. The FOREX market is considered an over the counter (OTC) or interbank market, due to the fact that the entire market is run electronically, within a network of banks, continuously over a 24-hours periods.#WHAT IS FOREX AND WHAT IS TRADED ON THE FOREX EXCHANGE
Consider following my forex blog 🙏
Drop the link
link