Playhead

A playhead is the marker that says now. It sits at the current position on a timeline and does two jobs at once: it reports where playback has got to, travelling on its own while media plays, and it accepts a drag to move playback somewhere else. In editing tools it is drawn as a head at the top of a vertical line that crosses every track in the stack, which is the shape the name comes from: the head of a tape machine, sitting over the moving tape.

The word is worth learning because it separates three parts people routinely collapse into one. The track is the groove, the fixed channel that states the whole duration. The playhead is the marker on it. The scrubber is the control the two make together, the thing a person actually operates, and this site’s own definition of it leans on the word: a track showing elapsed and buffered time with a playhead you drag. Web developers use all three every day in a video player without ever learning the middle one, because HTML gives them a <video> element with the parts already assembled and no names for its insides. Video editors, digital audio workstations and animation tools all say playhead and expect you to know it.

There is a real design decision hiding in that double job. A marker that reports position and a marker that accepts input want different sizes: the line wants to be one or two pixels so it reads as an exact instant, and the grab target wants to be thirty or forty so a person can hit it. The usual answer is a wide head at the top of a thin stem, with the hit area belonging to the head and often to the whole vertical band around the line. The same split explains why the line usually sits above every track in z-order and why it is drawn in a colour used nowhere else in the editor.

Two behaviours are worth getting right. First, dragging the playhead should take over from playback rather than fight it: the drag pauses the travel, the position follows the pointer, and playback resumes from wherever it was dropped. Second, the marker should not lag. A playhead animated with a transition eases toward the position it has already reached, which turns an exact instant into a guess, so its position is set every frame and its movement is never eased. If the timeline can be zoomed, the playhead is also what the view scrolls to keep in sight, which is why it usually owns the auto-scroll rule rather than the tracks do.