In still photography, the panning technique is used to suggest fast motion, and bring out foreground from background. In photographic pictures it is usually noted by a foreground subject in action appearing still (i.e. a runner frozen in mid-stride) while the background is streaked and/or skewed in the apparently opposite direction of the subject’s travel. (Wikipedia)
I have learnt of this technique for quite sometimes, but I had never practiced it, not until last week when I had chances to pan children running at school. Even my constant f/2.8 fast lens could not compensate the low light condition (children run under tree shades) and fast running. To some degree, I could freeze their action, but it was not sharp enough. Then I came up with the idea of panning. After a few trial shots, I started to love it. I panned at the speed of about 1/100 to 1/60 sec.