What is margin?

Margin is the amount required to open and maintain a leveraged trading position. It is the difference between the full value of your position and the capital provided to you by a broker or leverage provider. The margin is the deposit required to use leverage products. Using leverage can allow you to take full market risk by investing only a fraction of a trade’s full value. The required margin is usually stated as a percentage.
The required margin at the beginning of a trade is usually referred to as the initial margin. So it is the minimum amount that needs to be deposited in the margin account at the beginning. Example: You want to open a position of 1 lot (€100,000) in EUR/USD. The leverage is 1:25 and is provided by the broker. Now divide the position size by the leverage. A margin of €4,000 is required for the position with 1 lot (€100,000).