Questions about soft body physics in Blender's soft body physics engine and Blender's game engine. Use this tag for question pertaining to soft body physics.
Soft body simulation is used for simulating soft deformable objects. It was designed primarily for adding secondary motion to animation, like jiggle for body parts of a moving character.
It also works for simulating more general soft objects that bend, deform and react to forces like gravity and wind, or collide with other objects.
While it can simulate cloth and other stiff types of deformable objects to an extent, the Cloth Simulation can do it better with a solver specifically designed for this purpose.
The simulation works by combining existing animation on the object with forces acting on it. There are exterior forces like gravity or force fields and interior forces that hold the vertices together. This way you can simulate the shapes that an object would take on in reality if it had volume, was filled with something, and was acted on by real forces.
Soft bodies can interact with other objects through Collision. They can interact with themselves through Self-Collision.
The result of the soft body simulation can be converted to a static object. You can also bake edit the simulation, i.e. edit intermediate results and run the simulation from there.
More information at the Blender Manual
