When trading Forex, you'll see that both 'Bid' and 'Ask' prices are quoted. The bid price is the price at which you can buy the currency, while the ask price is the price at which you can sell it. If you are purchasing a currency in a trade, this is known as a long trade, and the hope is that the currency pair will increase in value, so that you can sell it at a higher price and make a profit on the difference.

Currency and exchange were important elements of trade in the ancient world, enabling people to buy and sell items like food, pottery, and raw materials.[9] If a Greek coin held more gold than an Egyptian coin due to its size or content, then a merchant could barter fewer Greek gold coins for more Egyptian ones, or for more material goods. This is why, at some point in their history, most world currencies in circulation today had a value fixed to a specific quantity of a recognized standard like silver and gold.

In 1944, the Bretton Woods Accord was signed, allowing currencies to fluctuate within a range of ±1% from the currency's par exchange rate.[29] In Japan, the Foreign Exchange Bank Law was introduced in 1954. As a result, the Bank of Tokyo became the center of foreign exchange by September 1954. Between 1954 and 1959, Japanese law was changed to allow foreign exchange dealings in many more Western currencies.[30]
There are two main types of retail FX brokers offering the opportunity for speculative currency trading: brokers and dealers or market makers. Brokers serve as an agent of the customer in the broader FX market, by seeking the best price in the market for a retail order and dealing on behalf of the retail customer. They charge a commission or "mark-up" in addition to the price obtained in the market. Dealers or market makers, by contrast, typically act as principals in the transaction versus the retail customer, and quote a price they are willing to deal at.
Due to Forex CFDs being leveraged, traders can access large portions of the currency market at a very low margin - sometimes as low as 1/500th of the size of the market they want to access (based on a leverage rate of 1:500). There are few additional costs as well - most Forex trading accounts have little (or no) commissions, order fees, and account management fees. If there are any trading fees, these are usually a markup the broker has added to the spread.
Unlike stock markets, which can trace their roots back centuries, the forex market as we understand it today is a truly new market. Of course, in its most basic sense - that of people converting one currency to another for financial advantage - forex has been around since nations began minting currencies. But the modern forex markets are a modern invention. After the accord at Bretton Woods in 1971, more major currencies were allowed to float freely against one another. The values of individual currencies vary, which has given rise to the need for foreign exchange services and trading.