What is CSS backface-visibility Property?

CSS - Interview Questions

The backface-visibility property defines whether or not the back face of an element should be visible when facing the user. The back face of an element is a mirror image of the front face being displayed. This property is useful when an element is rotated.

Example :

#div1 {
   backface-visibility: hidden;
}
#div2 {
   backface-visibility: visible;
}