Tweening is the process of filling the gaps between the key sequences, i.e between the keyframes that are already created. Keyframes are those frames that represent start and end point of animation action. Tweening involves generating intermediate keyframes between two images that give the impression that the first one has evolved smoothly to the second image. For this purpose, we use properties like transforms - matrix, translate, scale, rotate etc.

In the below example, we are generating intermediate frames of paragraph elements to SLIDE through from the start to the right edge of the browser.

Here, the paragraph element specifies that the animation process should take 2 seconds for execution from start to the finish. This is done by using the animation-duration property. The animation-name of the @keyframes is DEFINED by using the property animation-name. The intermediate keyframes are defined by using @keyframes rule. In the example, we have just 2 keyframes. The first keyframe starts at 0% and runs till the left margin of 100% which is the rightmost edge of the containing element. The second keyframe starts at 100% where the left margin is set as 0% and the width to be set as 100% which results in finishing the animation flush against the left edge of the CONTAINER AREA.