_ is the concept of sending extra bits for use in error detection.

Redundancy allows a receiver to check whether received data was corrupted during transmission. So that he can request a retransmission. Redundancy is the concept of using extra bits for use in error detection. The redundant bits are added by sender and removed by the receiver. Instead of repeating the entire data stream, a shorted group of bits may be appended to the end of each unit. This technique is called redundant because the extra bits are redundant to the data : they are discarded as soon as the accuracy of the transmission has been determined.