All foreign exchange transactions are made Over-the-Counter.
There is always a counter party for any orders and “Supply” and “Demand” for all transactions.
As the basic rule of economics, if the number of “Demand” is larger than “Supply”, then the price goes up and vice versa.
You can say that more popular currencies are more expensive and its popularity depends on many aspects of the world.
Factors that change a Currency Price
Currency prices (exchange rates) are affected by a variety of economic and political conditions, most importantly interest rates, inflation, and political stability.
Moreover, governments sometimes participate in the Forex market to influence the value of their currencies, either by flooding the market with their domestic currency in an attempt to lower price, or conversely buying in order to raise the price.
This is known as Central Bank intervention.
All of the above can cause high volatility and price movement in Forex markets.
No one can control the Market
There are certain motives that drive the Forex market to certain directions though, as the scale of the market is so big, no one can completely control the market.
Even a Mega bank or a Government are not capable of doing that.
You can find the list of FX and CFD brokers in the link above.
To start investing, you may only need a few dollars as the minimum amount of investment.
Or you can also start your Forex trading with “No Deposit Bonus” which you can get for free just by opening an account.