Which characteristic distinguishes Transmission Control Protocol (TCP) from User Datagram Protocol (UDP)?

The characteristic that distinguishes Transmission Control Protocol (TCP) from User Datagram Protocol (UDP) is that TCP includes mechanisms for ensuring reliable data transmission, which entails the automatic retransmission of lost packets. This reliability is achieved through a series of acknowledgments and retransmission requests. If a packet is not acknowledged within a certain timeframe, TCP will automatically resend that packet to ensure that all data is eventually received correctly.

In contrast, UDP is designed for speed and efficiency in transmitting data, often used for applications like video streaming or online gaming where speed is more critical than reliability. These applications may tolerate some data loss and do not have built-in mechanisms for retransmission or acknowledgment, which is why it is considered faster and more suitable for scenarios where timeliness takes precedence over accuracy.

By focusing on retransmission and acknowledgment, TCP provides a connection-oriented service that guarantees data integrity and order, making it the preferred protocol for applications needing such reliability.