Motion blur is the smearing of moving objects within a single frame. A spinning car wheel doesn't appear as a sharp set of spokes — it appears as a soft circular smear. A waving hand doesn't appear frozen mid-air — it appears slightly blurred along the direction of motion. The effect is physical: it happens because the camera shutter is open for some fraction of a second while the object moves across the frame.
In cinema, motion blur is the secret ingredient that makes 24 fps look like film. The standard cinematic shutter is open for half the time between frames (a "180-degree shutter angle"), producing exactly enough motion blur that fast action reads as natural motion to the human eye. Take that motion blur away — for instance by shooting at 24 fps with a very fast 1/2000 second shutter — and the result feels jittery and unreal, like a stop-motion animation. Take it the other way and you get a soft, dreamy "everything's smeared" look used for stylistic effect.
For a product team, motion blur is mostly a capture decision, not an encoding one — once the blur is baked into the frames, no encoder removes it cleanly. Two practical implications. First, frame rate alone doesn't determine "cinematic look": 60 fps with a fast shutter looks twitchy, 24 fps with proper shutter looks filmic, and many viewers prefer the latter for narrative content. Second, AI motion-interpolation features on TVs and streaming services try to synthesise motion blur (or remove it) algorithmically — sometimes well, often with uncanny-valley results. The aesthetic decision belongs at the capture stage; everything downstream just preserves or destroys what was already there.
