What does the scaleZ() CSS transform function do?

Question

I’m trying to wrap my tiny brain around 3D CSS transforms, and I‘m having trouble understanding what the scaleZ() function is for.

scale(),

Answer 1

there are three views in over webpage X, Y & Z like for example z-index as it's same thing the scaleZ().

Check what w3c say

scale([, ])
specifies a 2D scale operation by the [sx,sy] scaling vector described by the 2 parameters. If the second parameter is not provided, it is takes a value equal to the first.
scale3d(, , )
specifies a 3D scale operation by the [sx,sy,sz] scaling vector described by the 3 parameters.
scaleX()
specifies a scale operation using the [sx,1,1] scaling vector, where sx is given as the parameter.
scaleY()
specifies a scale operation using the [1,sy,1] scaling vector, where sy is given as the parameter.
scaleZ()
specifies a scale operation using the [1,1,sz] scaling vector, where sz is given as the parameter. 

check your link animation http://www.webkit.org/blog-files/3d-transforms/morphing-cubes.html

EDIT:

your fiddle still not explain what is scaleZ() because we can get that effect from scaleY() also.

Check this fiddle http://jsfiddle.net/sandeep/dppNn/

Now in my fiddle example you can the 3rd digit box look like 3D means with scaleX(),scaleY() & scaleZ() & 2nd digit box look like 2D because they scale only scaleX() & scaleY().