It is very important that the individual wanting to trade foreign exchange be aware of the very marked difference between speculation and investment. Foreign exchange trading is by nature a speculative occupation. Foreign exchange markets are amongst the most volatile markets in the world. When traded on a margined basis they effectively become the most volatile in the world.

Day trading in foreign exchange can be extremely profitable and high-risk profile traders can generate huge percentage returns even overnight. Day trading is however a mentally and psychologically challenging activity and is by no means meant for everyone. Day trading is essentially speculation and day traders essentially only do that: day trading. Most people who trade foreign exchange are not professional day traders however.

Often the contractors of foreign exchange brokerage services are professionals in some capacity or other. These people do not day trade but take the occasional position from time to time. This is also speculation and should not be confused with making an investment.

The conclusion here is that the nature of foreign exchange trading not lend itself as much to investment as it does to speculation and hedging (hedging may be performed in forward instruments). It is possible in a sense to make an investment in foreign exchange over a long-term period but this necessitates a large account value and low leveraging.

Recommended further reading:
Advantages
Origins
Who participate in Forex Trading?
Main Forex Markets
Market Dynamics
Margin Trading
Trading with a Strategy
Risks inherent to Forex
Forex abbreviations