Forex is open 24 hours a day and one can trade at any time. But why all the bigest price moves take place during London and NY sessions? If forex is open 24 hours traders dont need to wait for any session or any particular time to trade. They can trade most actively any time they want, but they stick to theese particular hours. Good when you understand the reason why something happens. It is like one uses the indicator only as green/red-buy/sell button, without understanding how this indicator is calculated. Just like axiom. Will be useful to know what forms the active market during the so called london and new york sessions.