What is currency trading?

Is it a bunch of crazy people standing in a small circular area yelling out seemingly random phrases and tossing papers as seen in the movies? Not so much. A more accurate picture would be a bunch of people in a room, each sitting in front of 3 to 6 computer monitors filled with charts. Someone is trading that desk almost all the time from 5pm on Sunday to 4pm Friday.
Here are some FAQs from Investopedia but the nuts and bolts are that the currency market is a worldwide, completely electronic market for the buying and selling of foreign currencies.
What makes it different from trading stocks, commodities, or options?
First, the hours. Depending on which broker you choose you can take trades 24 hours a day from 5pm Sunday to 4pm Friday. How is this? The market services the entire globe so when the east coast of the U.S. is finishing dinner the Asian markets are just getting warmed up. An hour or so before they call it a day the London session kicks into gear and takes us well past the traditional start of the trading day in America.
Second, the volume. Depending on who you talk to the average daily dollar amount of trades is anywhere from US$2 trillion to US$3.5 trillion. Compare that to the highest monthly dollar volume the NYSE Group has had in the past 5 years of US $3.6 trillion. When you take this extremely high volume and divide it across the 20 to 30 pairs able to be traded at most currency brokers, instead of the thousands of stocks listed on any given exchange you get one beautiful thing....liquidity.
Third, the leverage. If you want to lever up (trade more shares of a stock than you can afford) in the stock market you have to have a fairly large account and have to borrow the shares on margin from someone, most likely your broker. Currency brokers provide automatic leverage from 50:1 to 400:1 or even higher. This is actually necessary in most instances anyway since the standard currency contract size is 100k. This makes the barriers to entry very small.