Provisional Ball
The provisional ball is your replacement ball when the first one may be lost or out of bounds.
The provisional ball is the rulebook's time-saving trick. If your ball flies towards out of bounds or into dense rough where it could be lost, you play a second ball immediately. You announce it expressly as provisional, otherwise it counts as the ball in play. The purpose: you do not first have to search, find out that the ball is gone and then take the long way back. The provisional is already lying in the right place.
The rules are simple and strict. You play the provisional, then search for the first ball for at most three minutes. If you find it in play, you continue with the original, the provisional is picked up. If the original is lost or out of bounds, the provisional becomes the ball in play, with a penalty stroke and loss of distance. An example: your drive curves towards the white stakes. You immediately play a second drive. The first is gone, you play the second and count stroke three.
A typical mistake is the missing announcement. If you do not say "provisional", the second ball automatically counts as in play, and the first is lost, no matter where it lies. Also popular: searching on past the three-minute limit. Many clubs additionally have a local alternative rule for lost balls and out of bounds that saves the way back. Whether it applies is stated on the scorecard or on the notice board.
FAQ
When may I play a provisional ball?
When your ball could be lost outside a penalty area or could be out of bounds. If you think the ball lies in a penalty area, the provisional rule does not apply, the relief rules for penalty areas apply there. If in doubt: announcing and playing a second ball costs nothing, but saves the way back.
What do I have to announce with the provisional ball?
Before the stroke you must clearly say that you are playing provisionally, for example "I am playing a provisional". Without this announcement the second ball automatically counts as the ball in play with penalty stroke and loss of distance, and the first ball is lost, no matter where it lies. A mere "I'll hit another one" is not enough.
How long may I search for the original ball?
Exactly three minutes from the moment you or your caddie begin the search. If you do not find the ball in this time, it is deemed lost and the provisional becomes the ball in play. You do not need a stopwatch, but searching significantly longer holds up the whole course.