Описание тега keyframe
Keyframes is a general term in animations that is used to refer to the starting point and the finishing point of an animated transition. Use alongside the [css] tag if you want to refer to the @keyframes rule used in CSS animations.
Keyframes in general are starting and ending points of a particular smooth animation transition.
In CSS, the @keyframes rule is used to create animations. The following URL elaborates the usage of keyframes in CSS: http://www.w3schools.com/cssref/css3_pr_animation-keyframes.asp