In telecommunications, asynchronous communication is transmission of data without the use of an external clock signal, where data can be transmitted intermittently rather than in a steady stream. Any timing required to recover data from the communication symbols is encoded within the symbols. The most significant aspect of asynchronous communications is variable bit rate, or that the transmitter and receiver clock generators do not have to be exactly synchronized.

Asynkroninen kommunikaatio (engl. asynchronous communication) eli ei-reaaliaikainen kommunikointi on kommunikointitapa, jossa kommunikoinnin osapuolet eivät ole ajallisesti toisistaan riippuvaisia eli ovat ajasta (ja paikasta) riippumattomia.