Hi Duanpatah, 

Thanks for your question. A Green in Regulation is when a golfer finds the green in a certain number of shots. It is assumed that a golfer will have 2 putts on each hole, so for a par three, a green in regulation would be hitting the green in 1 shot, on a par 4 in 2 shots and on a par 5 in 3 shots. 

Obviously a golfer is more likely to make Par or better if they hit the green in regulation. Hence, the more greens in regulation you have in your round, the more likely you are to shoot better. 

I hope this is helpful. Let me know if you have any other questions. 

Tom Hutton
Team Titleist South East Asia Manager