A keyframe is a starting or ending point in a video animation encapsulating a specific display state (such as camera position, object visibility, color and rendering mode). Transitions are interpolated between keyframes for creating a video animation.
In Aivia, keyframes are used in the Video Animator tool for creating videos for visualizing a 3D/3D+time dataset. Each keyframe is shown as a screenshot / thumbnail on the video timeline with additional tools for modifying the keyframe.