To trade $100,000 of currency, with a margin of 1%, an investor will only have to deposit $1,000 into her or his margin account. The leverage provided on a trade like this is 100:1. Leverage of this size is significantly larger than the 2:1 leverage commonly provided on equities and the 15:1 leverage provided in the futures market. Although 100:1 leverage may seem extremely risky, the risk is significantly less when you consider that currency prices usually change by less than 1% during intraday trading (trading within one day). If currencies fluctuated as much as equities, brokers would not be able to provide as much leverage.
Currencies are traded on the Foreign Exchange market, also known as Forex. This is a decentralized market that spans the globe and is considered the largest by trading volume and the most liquid worldwide. Exchange rates fluctuate continuously due to the ever changing market forces of supply and demand. Forex traders buy a currency pair if they think the exchange rate will rise and sell it if they think the opposite will happen. The Forex market remains open around the world for 24 hours a day with the exception of weekends.