Every trader has drawdowns; the question is how deep and how long. Drawdown is measured from the highest equity point (the high-water mark), and the recovery needed grows faster than the loss: -10% needs +11%, -25% needs +33%, -50% needs +100%.
prop-firms enforce a daily-drawdown and a max-drawdown as hard limits. Personal traders should set their own.
Example: an account grows from $10,000 to $12,000, then falls to $10,200. The drawdown is $1,800, or 15% from the peak, even though the account is still above its start.
Related: max-drawdown, daily-drawdown, risk-of-ruin, risk-management