The US Dollar (USD) and Euro (EUR) are official currencies of their respective economic zones in the US, and the nations within the European Union. The FOMC (Federal Open Market Committee) is a branch of the Federal Reserve (FED) that determines the direction of monetary policy for the US, which in turn impacts the value and perceived value of the US Dollar. The European Central Bank (ECB) is the main central bank for the Euro and the Euro zone, and has a similar impact on the Euro currency.
Both currencies are part of the Foreign Exchange (Forex) market. In the Forex market, the price of one currency moves up, down, or sideways versus another currency, which is referred to as a currency pair. The Euro (EUR) and the US Dollar (USD) form a currency pair which is known as the Euro/Dollar, EURUSD or EUR/USD. Both the EUR and the USD also form currency pairs with other currencies such as, the Euro versus the Great British Pound (EUR/GBP) or the US Dollar versus the Canadian Dollar (USD/CAD).
The Euro Dollar is the most-traded currency pair in the Forex market, and its value refers to the exchange rate of the euro against the US dollar.