A keyframe is a specific frame in animation or video editing that marks the start or end point of a transition. It defines important positions or states of an object, such as its location, rotation, or scale, at a particular moment in time. By setting keyframes, animators can create smooth movements and changes over time. In computer graphics, keyframes are essential for creating animations in software like Adobe After Effects or Blender. They allow artists to control the timing and flow of animations, making it easier to produce complex sequences without manually adjusting every single frame.