In the world of Forex trading, margin is like the deposit you put down to rent a high-powered car - it's the collateral that lets you control a much larger position than your actual cash would allow. At its core, margin is a portion of your account equity that your broker "holds" as security to open and maintain trades.
It's expressed as a percentage of the full trade value and is essential for leveraging your capital. To break it down, margin ties directly to leverage that brokers offer.