Stop-and-Wait ARQ is a simple error control protocol used in data communication. In this method, the sender transmits a single data packet and then waits for an acknowledgment (ACK) from the receiver before sending the next packet. This ensures that each packet is received correctly before proceeding, reducing the chance of errors. If the sender does not receive an ACK within a specified time, it assumes the packet was lost or corrupted and retransmits it. This process continues until the sender receives a valid acknowledgment, making Stop-and-Wait ARQ straightforward but potentially inefficient for high-latency networks.