ICM—in camera motion—is a technique used to add interpretive aesthetics to an image by moving the camera during exposure while the shutter is open. Generally, the effect created is impressionistic. The shutter speed duration must be long enough for the motion to register in the capture, typically 1/3 of a second or longer.
ICM effects can be accomplished with the camera on a tripod or—more often—handheld. The direction and speed of motion in relation to the subject matter is crucial. ICM is hit-or-miss: you can expect many essays for each good result.
The Tall Trees image below is an ICM image made on my iPhone with a shutter duration of about one second via the Slow Shutter Cam app. Motion was steadily from top to bottom, elongating this already impressive aisle of trees.
ICM is for iPhones too!