The order in which bits are sent is important with respect to burst errors. Burst errors are errors that affect several bits that are close together. In the real world, burst errors are common and may be caused by a blip of electromagnetic noise or a scratch on a CD for example.


CRCs are designed to be good at detecting burst errors. But for this to work correctly, the bits of a message must be fed into the CRC generator in exactly the same order as they are transmitted/stored.