The forex market is the largest and most liquid financial market in the world. Since the gold standard was abandoned in 1971, exchange rates started floating and currency trading therefore became possible for banks and large financial institutions.
Since 1990, forex trading has become within everyone's reach, thanks to the development of the Internet and the arrival of new online brokerage firms. Nowadays, individual traders such as you and me can speculate on currency movements through a broker and a trading platform. These forex brokers offer lot sizes that are suitable for small investors. However, speculating on exchange rates is not for all traders due to leverage-related risks and a lack of experience.
Unlike stock markets, currency trading is not centralized on a regulated marketplace. There are therefore no clearing houses as is the case with traditional exchanges, forex participants trade with each other through an electronic interbank network, in OTC mode (Over-The-Counter).
Here are some articles on the advantages of currency trading and how it works.