Synchronous serial communication

Synchronous serial communication describes a serial communication protocol, "In synchronous transmission, groups of bits are combined into frames, and frames are sent continuously with or without data to be transmitted." Synchronous communication requires that the clocks in the transmitting and receiving devices are synchronized – running at the same rate – so the receiver can sample the signal at the same time intervals used by the transmitter. No start or stop bits are required.

Source: Wikipedia — Synchronous serial communication (CC BY-SA 4.0)