Serial and parallel transmission

Data transmission over the communication line can be arranged sequentially or in parallel.

• In parallel data transmission, data bits are sent simultaneously over several parallel channels of the same communication line. 

• In serial data transmission, data bits are sent over one channel in turn.

• At first glance, it seems that parallel data transmission should be chosen, since it should be faster than serial. However, in practice, in the vast majority of cases, serial data transmission is chosen for laying computer networks. 
A communication line with one channel is cheaper than a communication line with several parallel channels. In addition, a communication line with one channel takes up less space than a communication line with several channels. Also, in the case of parallel channels, it is necessary to ensure their operation at the same speed, otherwise the initial order of bits will be confused at the output and the data will be damaged.