A unit of transmission rate for radio signals, especially for the transmissions between satellites and ground stations. In the simplest form of transmission, data can be sent in bits, which have only two states (on or off). To increase data transmission rates as much as possible, information is sent in units called "symbols", which have a number of states, so that each symbol can include several bits of information. In practice, transmission rates are usually stated in ksym/s (thousands of symbols per second) or Msym/s (millions of symbols per second). See also baud and bit per second