A putter is a club used in the sport of golf to make relatively short and low-speed strokes with the intention of rolling the ball into the hole from a short distance away. It is differentiated from the other clubs (typically irons and woods) by a clubhead with a very flat, low-profile, low-loft striking face, and by other features which are only allowed on putters, such as bent shafts, non-circular grips, and positional guides.
Putters are generally used from very close distances to the cup, generally on the putting green, though certain courses have fringes and roughs near the green which are also suitable for putting. While no club in a player’s bag is absolutely indispensable nor required to be carried by strict rules, the putter comes closest. It is a highly specialized tool for a specific job, and virtually no golfer is without one.