What are floating bones for?

Floating bones are created between fixed bones to create "floating fixed bones". By using floating bones, you can arbitrarily specify the position of fixed bones without creating extra fixed bones. Floating bones are not added as animation bones, which also helps to reduce data weight.

In animation editing, floating fixed bones can be moved independently of their parents. It is used when you want to move distant meshes.

It is also relevant during IK operations. The IK bone influence range extends to the fixed bone where the parent bone hits the floating bone.

Moving the leftmost axis affects all connected fixed bones up to the red circle.