rubbish78:

Form III: Soresu
Soresu is the third form of classical Lightsaber combat and is regarded as the most defensive. Form III originated as set of stances and maneuvers designed to counter incoming blaster fire. As the form developed into a more mainstream combat style it became more popular and eventually progressed into the defensive form it is today. Unlike most other forms, Soresu focuses almost exclusively on defense and parries with few attack actions. It has been said a true master of Soresu would be virtual invincible.
It has been said that the only reason any Jedi survived the Clone Wars
at all was due to Soresu. They certainly did not win, but the
impossibly strong defensive styles of Form III meant many evaded
ultimate defeat. (x)