Definitions for "FLASH SYNCHRONIZATION"
The synchronization of firing of the flash and the shutter release so that the peak flash intensity occurs while the shutter is open.
Timing of the closing of the flash contact inside the shutter so as to make the peak brightness of the flash coincide with the maximum shutter opening at instantaneous shutter speeds.
Simply the function of the timing of the flash coinciding with the shutter release. There are two types of synchronization: Front Curtain Sync, which activates the flash at the start of the exposure and a Rear Curtain Sync that triggers the flash at the end of the exposure.