What is isolated margin?

A margin mode where each position has its own margin: if it is liquidated, the rest of the account is untouched.

With isolated margin you allocate a fixed amount to a position. The most you can lose on it is that amount, but the liquidation price is closer than with cross margin, because the position cannot draw on the rest of the balance.

Traders use isolated margin for risky bets that should not put the whole account at risk.