FOMC is an important meeting that decides each month the Federal Fund Rate and the money supply.
FOMC stands for Federal Open Market Committee of the Federal Reserve Bank of USA (FED).
Fund Rate is the short term overnight interest rate that banks charge each other for making the deposit with FED.
This short term interest rate dictates the medium term and the long term interest rates in the US economy.
FED decides about the money supply with the sale/purchase of US Treasury Bills.
If there is an interest rate increase announcement in FOMC meeting, this can move the USD pairs big time.
Most of the time FOMC Meeting ends with no major decision in which case currency market whipsaws with no clear direction.
Read this blog post in which I explain how to trade FOMC Meeting and know when the market is going to move big time.