Briefly describe the different methods for synchronizing communication between two devices

What will be an ideal response?

Synchronous: In a synchronous transmission, the internal clocks of both devices are synchronized before transmission begins.
Asynchronous: In an asynchronous communication, the sending device sends a starting bit; the receiving device then starts its internal clock when it receives the starting bit to time the message.
Isynchronous: In this method, both devices use the same external source for timing.