What exactly do the words "balance," "equity," and "margin" mean?
Balance: The total amount of cash accessible for trading, including all closed out winnings and losses, as well as any deposits and withdrawals made on your trading account.
Margin means the amount of money necessary to open a position. It gives you leverage.
Equity - Margin held on open trades is referred to as free margin.
Margin level (% free margin): (Equity / Margin kept on open transactions) x 100