I do understand that ease-in mean that the animation start slow, ease-out ending slow, and ease-in-out starting slow and ending slow.

But what is the meaning of the four values in the cubic-bezier?
w3school say:
cubic-bezier(n,n,n,n) Define your own values in the cubic-bezier function. Possible values are numeric values from 0 to 1.
http://www.w3schools.com/cssref/css3...g-function.asp

But that doesn't explain much?

can anyone explain to me what is the meaning of every value in the cubic-bezier?