In the context of data transfer an asynchronous signal is referenced to no external clock or timing information. There is no guarantee of time taken but a transfer uses only small resources as these are shared with many others. A transfer is ‘stop-go’ – depending on handshakes to check data is being received before sending more. Ethernet is asynchronous. Being indeterminate, asynchronous transfers of video files are used between storage devices, such as disks, but are not ideal for ‘live’ operations.
See also: Ethernet, Isochronous, Synchronous