On a margin account on some exchanges, you might see the options for Cross and Isolated Margin. If you choose Cross Margin when entering a trade, that means that you want the rest of your account's equity to support the margin of that trade.

Say you have $10,000 in your account, and the price of bitcoin is $10,000. You go long $1,000 on bitcoin with 10x leverage, meaning you open a position of $10,000 or 1 bitcoin. With Isolated Margin, your position would close when the price of bitcoin dropped 10% (10% * 10 = 100%) ato $9,000 and you'd lose all $1,000—even if the price then bounced up to $11,000.

With Cross Margin, your entire account would act as collateral for the trade. So if you bitcoin dropped down to $8000, your $1,000 margin would be fully utilized, and $1,000 of your equity would be utilized as well. If you manually closed the trade you'd be down $2,000.

Cross Margin lets you keep margin trades open despite big price fluctuations, and keep you from hitting margin calls. But put you at a greater risk of capital loss. They also let you freely use your equity for other trades in the meantime.