Selective Repeat is a data link layer protocol used in computer networks to ensure reliable data transmission. It allows the sender to transmit multiple frames before needing an acknowledgment for the first one. If a frame is lost or corrupted, only that specific frame is retransmitted, rather than all subsequent frames, improving efficiency. In Selective Repeat, both the sender and receiver maintain a buffer to store frames. The receiver can accept out-of-order frames and will acknowledge received frames individually. This method reduces the number of retransmissions and enhances overall throughput, making it suitable for high-speed networks.