For a young, untrained horse lunging is a method of teaching the animal to respond to the owner's voice and body language, while becoming familiar with all the aspects of working.
For older horses lunging is sometimes used to settle them before riding, or to get exercise when riding is not possible for some reason.
Lunging is also an aid for the riding instructor, helping to train riders in refining their seat and balance.
Whatever the case, it must be remembered that lunging is for training purposes and not for fun!
Lunging equipment consists of a cavesson or halter, a lunge line of around 30 feet (10m) long, and a light, long whip.