Motion blur
Movement recorded as a streak during a slower exposure, turning speed, traffic, water, or a moving body into a visible path.
See it
What it is
Motion blur is the streak a moving subject records while the shutter stays open. A fast shutter cuts movement into a crisp instant; a slower one gathers several positions into one trace. The direction and length of that trace show how the subject moved through the frame.
Reach for it when movement is the subject: traffic trails, a dancer's hands, water, crowds, or a cyclist against a rushing street. Lock the camera for sharp surroundings, or use the panning technique to follow the subject and turn the background into horizontal streaks. Video has its own convention, the 180-degree shutter rule, which sets shutter speed to roughly double the frame rate so movement blurs the way an audience expects.
Gotcha: camera shake and subject motion are different blurs. A tripod or stabilizer fixes only the first. Slow shutters also admit more light, so daylight may need an ND filter, and the moving shape still needs one recognizable sharp area or it can collapse into an accidental smear.
Ask AI for it
Create a panning photograph of a cyclist at 1/15 second: track the rider smoothly through the exposure so the face and torso stay recognizable while the street stretches into continuous horizontal motion blur. Use a 50mm lens, low ISO, and an ND filter in daylight. Keep wheel blur circular and directionally correct, with no duplicated limbs.