A provisional ball is an additional ball played under Rule 27 for a ball that may be lost in a water hazard or out of bounds. It is a way to save time and avoid having to walk back to the original spot of the ball if it is lost or out-of-bounds. Here are some key points to keep in mind about provisional balls:

• You can play a provisional ball when your ball might be out of bounds or lost.
• Before playing a provisional ball, you must tell another person in your group that you want to play a provisional and play it before you go forward to look for your original ball.
• If you find your original ball within five minutes somewhere outside of the out-of-bounds area, you should play the original ball. If the original ball is out of bounds, you should play the provisional ball.
• You must use the word “provisional” or otherwise clearly indicate that you are playing the ball provisionally under Rule 18.3.
• You can continue to play your provisional ball until you reach the place where your original ball is likely to be.
• If you make a stroke at your provisional ball at or beyond the point where your original ball is likely to be, the provisional becomes your ball in play under penalty of stroke and distance.

Overall, a provisional ball is a way to save time and avoid having to walk back to the original spot of the ball if it is lost or out-of-bounds. It is important to follow the rules and guidelines for playing a provisional ball to avoid any penalties or confusion.