In digital communications, a symbol is the smallest unit of data transmitted at one time.

In the simplest modulation schemes such as binary phase-shift keying, only one bit of data (i.e., a 0 or 1) is transmitted at a time depending on the phase of the transmitted signal. However, in a more complex scheme such as 16-QAM, four bits of data are transmitted simultaneously, resulting in a symbol rate (or baud rate) that is equal to one quarter of the bit rate.

Data transmission

Simbolo (telecomunicazioni)