|1. Asynchronous is a variable or random time interval between successive characters, blocks, operations, or events. Asynchronous data transmission provides variable inter-character time but fixed inter-bit time within characters.
2. In a communication sense,the ability to transmit each character as a self-contained unit of information,without additional timing information.This method of transmitting data is sometimes called start/stop.Synchronous working involves the use of timing information to allow transmission of data which is normally done in blocks.Synchronous transmission is usually more efficient than the asynchronous method.