What is FreeSync?

In high-frame-rate FPS games, screen tearing can often occur, where parts of the screen at the top and bottom seem misaligned, resembling two randomly overlaid images. Each frame of the image is displayed pixel by pixel from left to right (though it's imperceptible to the human eyes due to speed). This can lead to stuttering when the frame rate generated is significantly lower than the monitor's refresh rate. Matching the refresh rate of the monitor with the output frame rate of the graphics card can perfectly prevent tearing. Vertical sync forces the graphics card to use the monitor's refresh rate as its operating frame rate to achieve a follow the monitor effect (at the cost of sacrificing some frames). FreeSync monitors enable AMD's graphics cards and APUs (Accelerated Processing Units) to dynamically control the refresh rate of the connected display. Monitors that support FreeSync synchronize with the game's refresh rate, with the upper limit being its maximum refresh rate, which adjusts as necessary.
You can refer to the official AMD website for more details: https://www.amd.com/zh-hans/technologies/free-sync-faq.
Note:
FreeSync requires a compatible AMD graphics card or APU system, and the connection cable needs to be a DisplayPort (DP) cable. NVIDIA also supports compatibility with FreeSync monitors.