Margin refers to the amount of capital needed to maintain an open position and is calculated based on the trade value converted into US Dollars (for US Dollar denominated accounts). The percentage margin required for any given trade will also be dependent on the leverage scale and corresponding margin percentage selected for the account. For example, a leverage of 50:1 will have a corresponding margin requirement of 2% of the value of the trade size (value in USD of nominal trade amount).
Trading on margin can both positively and negatively influence your trading experience as both profits and losses can be substantially increased.