Currency trading, known as foreign exchange trading or forex, was once the territory of a select few.
But a technological revolution, access to better information, lower trading costs and greater transparency have all helped bring greater numbers of traders to the global foreign exchange market.
Foreign exchange, also known as FX, was never meant to be regarded as an investment asset.
What changed along the way to it becoming the truly global market it is? At $5tn in daily turnover, the FX market has no equal in size or liquidity, but can foreign exchange truly be regarded as an asset?
It's an important consideration when looking at how the market became democratised – open to all.
In the forex club
Even as recently as 20 years ago, forex trade was carried out by a relatively small number of institutional players.
It's prime function, at the most basic level, was the transfer of cash across national borders between counterparties, usually to fund business capital expenditure, cross border deals and other international transactions.
This process has traditionally been carried out by banks and other institutions, but once a bank learns how to profit from a process, it engineers ways of manufacturing revenue streams very quickly.
Banks charged commission for small transfers – perhaps for foreign trips.
For larger transactions – such as converting a few million pounds into the equivalent amount of dollars for cross border business – traders found they could extract profit from the exchange rate alone.
"It's no longer just about making people's money move," says Roger Rutherford chief operating officer at ParFX.
"There is a profit that can be extracted from this. Those FX desks that were just there to move money started to make a revenue line so they built out spot desks."
He adds: "So from a historical perspective I think FX became an asset class in its own right pretty quickly."
Gaining access to FX
Forex-based derivatives were available, but required specialist knowledge and trading in these instruments were mostly limited to financial and corporate counterparties looking to use them to hedge currency exposures.
And before the widespread use of retail trading platforms, large amounts of initial margin were required to proceed.
Yet it was in these over-the-counter products that private investors could get a first taste of a market hitherto closed to them.
Growth also in forex-related mutual funds and exchange traded funds helped private investors get a first taste of currency markets.
The financial crisis
It's impossible to discuss the development of any market without noting the impact of the financial crisis on it.
With interest rates reduced to historic lows around the world, long-term investors were no longer able to find yield in the fixed income markets.
"It made sense for people to look at what was already a large and liquid market, and look at the opportunity for yield that was not being found in other asset classes," says David Campbell, head of capital markets strategy at Broadridge.
Volatility increased and wiped out profits in many of the riskier trading strategies, such as the carry trade, where currencies in countries with low interest rates are sold to fund purchases of higher yielding currencies.