Panning
Following a moving subject with the camera during a relatively long exposure, so the subject stays sharp and the background streaks.
Measured in
seconds
In depth
Panning conveys speed more effectively than freezing does, because the streaked background gives the eye a reference for the movement. The technique needs a smooth continuous swing from the hips, started before the shutter and continued after it, and a shutter speed slow enough to streak the background but fast enough to hold the subject.
Examples in practice
A motorcycle panned at 1/60 s is rendered sharp against a completely dissolved crowd and barrier.