Scene markers are visual indicators displayed in the frame ruler at the top of the Timeline view.
You can use scene markers to highlight, sort and label parts of your scene. For example, you can indicate the frames you want to clean up, a change in action, an impact, or where you intend to apply an effect.
Scene markers have a colour, a name, a start frame, a length and a description. Then can mark a single frame or span over any amount of frames. If you hold the mouse cursor over a scene marker, its name, starting frame, duration and note will be displayed in the tool tip box.