As you will know if you have ever exchanged currency for a vacation, the rates are constantly changing. For example you may change $100 into another currency planning to travel, and then find that you do not need it and change it back. The rate will probably have changed in the meantime and you may even have made a profit.
Forex traders deal in currencies hoping to make a profit all of the time, but instead of changing money at the bank they use a broker. Most transactions these days are handled online. In many ways it is not so different from stock trading. There is the same potential to trade in margins where a small balance held by your broker can control much larger deals.
One difference from stock exchange trading is that forex traders are not limited to dealing in their own country. You can trade any two currencies regardless of where you live. This also means that the market is international. Because of time zone differences, it is open 24 hours a day from Monday morning in Australia to Friday afternoon in New York.
Each currency is represented by 3 letters: USD for the US dollar, GBP for the British pound, EUR for the Euro, JPY for the Japanese Yen, CHF for the Swiss franc, CAD for the Canadian dollar, AUD for the Australian dollar etc. The exchange rate between two currencies may be expressed like this: USD/CHF 1.14. This means that to buy one US dollar you will need 1.14 Swiss francs.
If you want to start out in forex trading you will need to look for a broker or investment management company that you trust. It is worth shopping around and checking online forums for recommendations. Check out how long the company has been in business and what your rights and liabilities will be. Read all of the fine print.