Margin
Collateral posted to open a leveraged position — the deposit that controls a much larger exposure.
Margin is the collateral you deposit to open and maintain a leveraged trade. Rather than paying an asset’s full value, you post a fraction as margin and borrow the rest of the exposure — the essence of leverage. Initial margin opens the position; maintenance margin is the minimum you must keep before facing a margin call or liquidation.
Crypto exchanges offer isolated margin (risk confined to one position) and cross margin (your whole balance backs positions). Margin trading is how small deposits control large positions — and how they get wiped out, since a modest adverse move can consume the entire margin.