The core idea
An uncovered call seller may have to deliver shares at the strike while buying them at a much higher market price.
A little more context
Assignment requires the seller to meet contract obligations. Early assignment is possible for some option styles.
What to remember
Learn settlement, multipliers, expiration, liquidity, and worst-case outcomes before considering real contracts. This course is education, not approval to trade.
Pause and reflect: how would you explain this idea to someone who has never invested?