You may have noticed that the value of currencies goes up and down every day. What most people don't realize is that there is a foreign exchange market - or 'Forex' for short - where you can potentially profit from the movement of these currencies. The best known example is George Soros who made a billion dollars in a day by trading currencies. Be aware, however, that currency trading involves significant risk and individuals can lose a substantial part of their investment. As technologies have improved, the Forex market has become more accessible resulting in an unprecedented growth in online trading. One of the great things about trading currencies now is that you no longer have to be a big money manager to trade this market; traders and investors like you and I can trade this market.
Individual retail speculative traders constitute a growing segment of this market. Currently, they participate indirectly through brokers or banks. Retail brokers, while largely controlled and regulated in the US by the Commodity Futures Trading Commission and National Futures Association, have previously been subjected to periodic foreign exchange fraud.[66][67] To deal with the issue, in 2010 the NFA required its members that deal in the Forex markets to register as such (I.e., Forex CTA instead of a CTA). Those NFA members that would traditionally be subject to minimum net capital requirements, FCMs and IBs, are subject to greater minimum net capital requirements if they deal in Forex. A number of the foreign exchange brokers operate from the UK under Financial Services Authority regulations where foreign exchange trading using margin is part of the wider over-the-counter derivatives trading industry that includes contracts for difference and financial spread betting.
NZDUSD is approaching its resistance at 0.6769(100% Fibonacci extension, 23.6% Fibonacci retracement, horizontal swing high resistance) where it is expected to reverse down to its support at 0.6714(horizontal swing low support). Ichimoku cloud is showing bearish cloud where a corresponding reversal is expected. Trading CFDs on margin carries high risk....
The value of a country's currency depends on whether it is a "free float" or "fixed float". Free floating currencies are those whose relative value is determined by free market forces, such as supply / demand relationships. A fixed float is where a country's governing body sets its currency's relative value to other currencies, often by pegging it to some standard. Free floating currencies include the U.S. Dollar, Japanese Yen and British Pound, while examples of fixed floating currencies include the Chinese Yuan and the Indian Rupee.
So, yes, at any given trading center, it's an eight hour day. But that really doesn't matter, because somewhere in the world trading centers are open. You can trade anytime you want, although you should also note that you'll get the narrowest spreads -- the broker's profit margin -- when the maximum number of trading centers are open or, more precisely, when the trading volume for your currency trade is greatest. 
The foreign exchange market is the "place" where currencies are traded. Currencies are important to most people around the world, whether they realize it or not, because currencies need to be exchanged in order to conduct foreign trade and business. If you are living in the U.S. and want to buy cheese from France, either you or the company that you buy the cheese from has to pay the French for the cheese in euros (EUR). This means that the U.S. importer would have to exchange the equivalent value of U.S. dollars (USD) into euros. The same goes for traveling. A French tourist in Egypt can't pay in euros to see the pyramids because it's not the locally accepted currency. As such, the tourist has to exchange the euros for the local currency, in this case the Egyptian pound, at the current exchange rate.