It is very like what people do when they are trading on the stock
exchange, in fact. Stock traders buy and sell stocks quickly with the
aim of making a profit. They do not wait for long term gains like
somebody might who was buying stock in a company as an investment.
Forex traders move in and out of the foreign currency market very
quickly too.
http://www.onlineforextradingadvice.com/Beginner-Forex-Currency-Trading.htm