Ilya Spivak in a very interesting seminar is discussing the concept of correlation between the Forex Market and other Financial Markets , it is useful and helpful for traders to know what is actually affecting the currency market and how it relates and respond to these other financial markets like stocks, commodities, Gold and other markets ..

I personally don't make a trade based on Forex Correlations but, it is useful as i said to be aware of the possible results of other markets that can affect the price action on your Forex chart .