Why do ohter bulbs go out also when one bulb is unscrewed?

When one bulb is unscrewed in a series circuit, it breaks the electrical path, causing all bulbs in that circuit to go out. In a series arrangement, the current flows through each bulb sequentially, so if one bulb is removed, the circuit is incomplete. This contrasts with parallel circuits, where each bulb operates independently, and removing one does not affect the others.