This keyword will start slow and speed up to normal by the middle.
This keyword will start slow, speeding up to fast in the middle, and then slowing back down to the end. This is the default value for this property.
The speed for this transition will remain consistent throughout.
This keyword will start normal and slow down toward the end.
This keyword starts and ends slow, but only hits normal speed in the middle.
This is the default value. The animation will play forward as expected.
The animation will play its steps working backward from last to first.
As long as the animation plays more than once, the direction will keep switching between forward and backward.