V-Sync (vertical synchronization) ties the GPU's framerate output to the refresh rate (frequency) of the display, which resolves screen tearing, but introduces stuttering. With a 60Hz display, this would force an FPS of 60, meaning the display will anticipate a frame precisely every 16ms. If the GPU misses this timing requirement (takes too long drawing the frame), the display will repeat the previous frame. This eliminates the chance of “tearing” by restricting the display only to drawing frames every refresh interval, but can cause stuttering when the 16ms window is missed (the display will repeat the previous frame).
V-Sync can introduce performance and stability issues, especially when the FPS output is already less than the monitor's refresh rate. V-Sync will lock the FPS to the monitor's refresh rate.